Here you will find dozens of hardness-related terms organized and cross-referenced for your convenience. If a word used in a definition is in red and underlined, that word has its own entry and you can click on the link to go to that entry.

A

Anorgasmia: The delay or absence of sexual climax (orgasm).

Abstinence, sexual: The voluntary decision not to engage in sexual relations of any kind. Reasons for abstinence include periodic abstinence for contraception, disease, or pregnancy prevention, and abstinence for religious reasons.

Adolescence: The period of transition from childhood to adulthood, describing both the development to sexual maturity and to psychological and relative economic independence. The World Health Organization uses the 10-19 year age range to define adolescence, with further divisions for early adolescence: 10-14 years, and late adolescence: 15-19 years.

Antibiotics: Medicines that kill infection-causing germs.

Antidepressants: Medications used to treat depression.

Anti-hypertensives: Medications used to treat high blood pressure.

Anti-inflammatory drugs: Drugs that reduce inflammation (swelling) by modifying the body's immune response.

Anus: The opening of the rectum to the outside of the body.

Arousal: Sexual excitement and stimulation.

Artery: A blood vessel that carries blood away from the heart.

Atherosclerosis: Deposition of lipids and plaque formation in arteries, leading to hardening and decrease in size of arterial lumen.

Autonomic nerve: A nerve with involuntary neural function, such as vasodilation.

B

Balanoposthitis: Inflammation of the head and the foreskin of the penis.

Blue vision: Distortion of color perception that results in increased blue color, typically after taking a higher dose of an erectogenic medication, such as Viagra or Levitra.

C

Celibacy: Abstinence from all sexual activity and sexual relations. For some, abstinence from sexual intercourse only.

cGMP: Abbreviation for cyclic guanosine monophosphate. A compound that promotes smooth vascular muscle relaxation.

Circumcision: A surgical procedure in which the foreskin (the skin that covers the tip of the penis) is removed from a male's penis.

Clitoris: The hooded body part at the top of the female genitals, above the urethra and below the pubic bone and hairline.

Coitus: (sexual intercourse, copulation, vaginal intercourse): Insertion of the penis into the vagina, followed by rhythmic movement often leading to orgasm.

Coitus interruptus: Withdrawal of the penis during penile-vaginal intercourse before ejaculation.

Condom: A flexible sheath (usually made of thin latex or polyurethane) designed to cover the penis (male condom) or vulva (female condom) during sexual intercourse for contraceptive purposes or as a means of preventing sexually transmitted infections.

Contraceptive: Barrier and non-barrier methods of preventing pregnancy and sometimes STIs.

Corona: The raised ridge on a penis that separates the glans from the shaft.

Corpus cavernosum: Spongy erectile tissue of the penis.

Corpus spongiosum: Tissue that runs on the underside of the penis and encapsulates the urethra.

Cowper's glands: Two small structures, attached to the urethra in the male, that secrete a few drops of clear, sticky fluid during sexual arousal.

Creatinine: A compound that is present in the blood, urine, and skeletal muscle.

D

Desire: The first stage of the sexual response cycle, characterized by a strong urge for sexual intimacy or satisfaction. Also called libido.

Digital rectal exam: A medical test done on males to determine the size of the prostate.

Dysfunction: Persistent or recurrent inability to react emotionally or physically to sexual stimulation in a way expected of the average healthy person or according to one's own standards of acceptable sexual response.

E

Ejaculate: The fluid, which includes semen and sperm, expelled from a man's penis during sexual climax (orgasm).

Ejaculation: A sudden ejection of fluid, especially semen, from the penis during sexual climax (orgasm).

Ejaculatory ducts: The structures formed by the fusion of the vas deferens and the seminal vesicles. The ejaculatory ducts empty into the urethra.

Erectile dysfunction: The inability to attain and/or maintain an erection suitable for penetration.

Erection: A penile condition characterized by enlargement and filling of erectile tissue with blood.

Erogenous zones: Highly innervated areas of the body that are especially sensitive and responsive to sexual stimulation, thus causing sexual arousal and sexual pleasure. Common areas identified as erogenous zones include neck, earlobes, mouth, lips, nipples, genitalia, buttocks, inner thighs, anus, backs of knees, fingers, and toes.

Erotic: Tending to arouse sexual desire.

Erotic fantasy: Reading, watching, imagining, telling or acting out sexual fantasies with or without a partner.

Estrogen: A sex hormone produced in the ovaries that stimulates the development of secondary female sex characteristics and has a role in puberty, menstruation, pregnancy, and contraception.

Excitement (arousal): This second stage of the sexual response cycle is characterized by increased heart rate and blood pressure, body muscle tension, sexual flush, and erection of the nipples in both sexes. In men, there is scrotal thickening and movement of the testes closer to the body. In women, vaginal lubrication and swelling of the vulva also occur.

F

Fellatio: The oral stimulation of the male genitals.

Flaccid: Referring to the non-erect, soft state of the penis when a man is not sexually aroused.

Foreplay: Physical and sexual stimulation (such as kissing, touching, stroking, and massaging) usually preceding sexual intercourse. See also outercourse.

Foreskin: In uncircumcised males, the additional layer of skin that covers the glans.

G

G-spot (Grafenberg spot): A small area on the front wall of the vagina that is especially sensitive to sexual stimulation in some women and may be the source of a small amount of fluid ejaculated at orgasm.

Gonads: The testes or ovaries (reproductive glands).

H

Hardness: The quality of a man's erection.

Heterosexual: One whose sexual attraction and desire is for people of the opposite sex.

Homosexual: One whose sexual attraction and desire is for people of the same sex.

Hormones: Chemical messengers dispersed by the blood that act on target organs. Main organs involved in hormone production are the pituitary, pancreas, ovary, testes, thyroid, and adrenal. Hormones have an effect on physiological functioning and psychological behavior.

Hyperlipidemia: Abnormally high levels of lipids in the blood.

Hypertension: High blood pressure.

I

Impotence: The repeated inability to get or keep an erection firm enough for sexual intercourse; now known as erectile dysfunction. The word "impotence" is often used to describe problems that interfere with reproduction, lack of sexual desire, and problems with ejaculation or orgasm.

Infertility: The inability of a man, woman or couple to conceive a child, usually after one year of trying.

L

Libido: The natural desire for sexual intercourse.

Lubricant: A slippery substance, typically oil- or water-based. A vaginal lubricant may be helpful for women who feel pain during intercourse because of vaginal dryness.

Lubrication: Moistening of the vaginal walls; the key indicator of sexual excitement in women.

M

Masturbation: Manual or other non-penetrative (penile) stimulation of oneself or a partner for sexual pleasure.

Monogamy: The practice of having only one partner.

Multiple orgasm: Passing immediately from the orgasm stage of the sexual response cycle to the plateau stage and back to the orgasm stage without passing through the resolution stage.

Mutual masturbation: Sexual activity in which partners stimulate each other's genitals with hands or sex toys. Sometimes used to refer to a couple watching each other masturbate.

N

Neurogenic: Originating in the nervous system.

Neurotransmitter: A chemical messenger used by nerve cells to transmit nerve impulses from one nerve cell to another.

Nitric oxide: A signaling molecule released by nerve endings during erection that allow the smooth muscle tissue in the penis to relax.

Nocturnal erection: Nighttime erections that naturally occur at all ages. Most men have three to five hard erections during deep (REM or rapid eye movement) sleep.

O

Orchiectomy: A surgical procedure to treat testicular cancer in which the doctor removes one or both testicles through an incision (cut) in the groin.

Oral sex: Sexual act in which one's mouth is used on another's genitals.

Orgasm: The fourth stage of the sexual response cycle, characterized by the peak of sexual tension, resulting in release of tension through muscular contractions of the urethra, anus, and pelvic floor in men and contractions of the uterus, vagina, anus, and pelvic floor in women. In men, orgasm can trigger contractions of the ejaculatory duct and prostate gland, causing semen to be ejected from the body through the penis.

Orgasmic platform: Congestion of blood vessels and tissue in the outer third of the vagina during sexual arousal; simultaneous contractions of the pubococcygeous muscles, anal sphincter, rectum, and perineum to form the orgasmic reflex.

Outercourse: Any form of sexual pleasure or stimulation between partners that does not include insertion of the penis into the vagina, anus, or mouth. Activities may include masturbation, erotic massage, rubbing together of body parts, and erotic fantasy.

P

Penile implant: Mechanical prosthesis that enables a man with erectile dysfunction to have erections.

Penis: Multipurpose male organ responsible for sexual pleasure, reproduction and elimination of urine and semen.

Peyronie's disease: An abnormal curvature of the penis due to the deposition of fibrous tissue in the elastic covering (tunica albuginea) surrounding the corporal penile bodies (cavernosa). The cause is unknown.

Phimosis: A condition in which the foreskin of the penis becomes constricted and difficult to retract.

Phosphodiesterase 5 (PDE5): Enzyme that breaks down cGMP during an erection, ultimately returning the penis to a flaccid state.

Phytotherapy: The use of plant-derived substances to treat medical conditions.

Premature ejaculation (PE): A condition in men characterized by persistent or recurrent ejaculation with minimal sexual stimulation before, on, or shortly after penetration and before the person wishes it.

Prepuce: The fold of skin that covers the head of the penis (also called the foreskin). Prepuce is also the hood or covering of the clitoris.

Priapism: Persistent, abnormal and painful erection of the penis.

Prostate (gland): A male sex gland located below the bladder and in front of the rectum. This walnut-shaped gland about an inch and a half long produces part of the fluid that is important for the production and transport of sperm.

Prostate cancer: Cancer of the prostate gland.

Prostate disease: A number of conditions of the prostate, including benign prostatic hyperplasia (BPH), prostatitis, and prostate cancer.

Prostate-specific antigen (PSA) test: A blood test that measures levels of the prostate specific antigen molecule in the blood. The test is used to screen for prostate cancer and to help monitor treatment.

Prostatectomy: Surgical removal of the prostate and some of the tissue around the gland.

Prostatitis: An acute, chronic, or noninfectious inflammation of the prostate. Symptoms include pain in the testicles, or rectal area and may sometimes include problems with ejaculation, urination, or defecation.

Psychogenic: Psychological.

Puberty: The state of physical development when sexual reproduction first becomes possible.

Pubescent: Having reached puberty.

R

Refractory period: The time immediately following orgasm during which a man cannot achieve an erection.

Retrograde ejaculation: A condition that occurs when, at orgasm, the ejaculate is forced back into the bladder rather than through the urethra and out the end of the penis.

S

Scrotum: The loose pouch of skin covered with pubic hair that contains the testicles.

Semen: The fluid that transports sperm.

Seminal vesicles: The sac-like pair of tiny glands that lie above the prostate and produce about 70 percent of seminal fluid for manufacture and transport of sperm.

Sensory: Relating to nerves that transmit signals to the central nervous system so that an organism has perception of self and the environment.

Sex : Refers to the biological characteristics that define humans as female or male. These sets of biological characteristics are not mutually exclusive as there are individuals who possess both, but these characteristics tend to differentiate humans as males and females. May also mean "sexual activity."

Sexual dysfunction: Any problem or condition that does not allow for a satisfactory sex life.

Sexual health: The many factors that impact sexual function and reproduction, including a variety of physical, mental, and emotional issues. Disorders that affect any of these factors can impact a person's physical and emotional health, as well as relationships and self-image.

Sexual intercourse: Sexual activity that involves vaginal, anal, or oral penetration.

Sexual response: Psychological and physical reaction pattern to sexual stimulation.

Sexual response cycle: The sequence of physical and emotional changes that occur as a person becomes sexually aroused and participates in sexually stimulating activities, including intercourse and masturbation. The sexual response cycle has four phases: excitement, plateau, orgasm, and resolution.

Sexuality: Involves giving and receiving sexual pleasure, as well as enabling reproduction. Sexuality is a total sensory experience, involving the whole mind and body--not just the genitals. Sexuality is shaped by a person's values, attitudes, behaviors, physical appearance, beliefs, emotions, personality, likes and dislikes, and spiritual selves, as well as all the ways in which one has been socialized.

Shaft: The main part of a penis.

Smegma: A thick, bad-smelling substance that results when oily secretions from the skin accumulate under the foreskin of the penis.

Smooth muscle: A type of involuntary muscle.

Sperm: The male reproductive cells.

Spermatic cord: The structure that secures the testicles within the scrotum.

Spermatogenesis: The process of producing sperm, the male reproductive cells.

Spermicide: A chemical in the form of a cream, gel, foam, film, or suppository inserted in front of a woman's cervix before sexual intercourse to prevent pregnancy. Spermicides block the cervix and paralyze the sperm, making them unable to travel into the womb.

STD: Sexually transmitted disease, passed on through sexual contact, also referred to as STI (sexually transmitted infection).

STI: Disease resulting from bacteria or viruses and often acquired through sexual contact. Some STIs can also be acquired in other ways (i.e. blood transfusions, intravenous drug use, mother-to-child transmission).

Syphilis: A sexually transmitted disease that can be acquired through sexual intercourse, kissing or other intimate bodily contact.

T

Tantric sex: Practices based on Hindu sacred text dealing with sexual yoga. In the Buddhist tradition, tantra refers to ritual texts that urge the cultivation of sensual pleasure.

Testicles (testes; singular testis): Part of the male reproductive system, the paired testicles manufacture the male hormones, including testosterone, and produce sperm, the male reproductive cells. The testicles are located inside the scrotum, the loose sac of skin that hangs below the penis. Hormones produced in the brain modulate testicular function.

Testicular self-examinations (TSE): A procedure to detect changes in the testicles by rolling them between the fingers and thumbs of both hands to check for any lumps.

Testicular torsion: A condition in which the spermatic cord gets twisted around a testicle, cutting off the testicle's blood supply. Symptoms of testicular torsion include sudden and severe pain, enlargement of the affected testicle, tenderness, and swelling. This condition requires emergency treatment.

Testosterone: The primary male sex hormone produced by the testes that is essential for sperm production and the development of male traits, including muscle mass and strength, fat distribution, bone mass, prostate function, and sex drive.

U

Undescended testicle: A condition in which the testicles do not descend from the abdomen, where they are located during development, to the scrotum shortly before birth. Also called cryptorchidism.

Urethra: The tube that carries urine from the bladder, and seminal fluid from the prostate and seminal vesicles out of the body.

Urinary tract infection (UTI): A condition that occurs when bacteria from outside the body get into the urinary tract and cause infection and inflammation.

Urologist: A doctor who is specially trained to treat male and female urinary tract disease, and male reproductive disease.

V

Vacuum erection device: A tubular device placed over the penis that creates a vacuum, drawing and trapping blood within the penis to produce an erection.

Vagina: The lower part of the female reproductive tract. The female organ of sexual intercourse where sperm are deposited.

Vas deferens (pl. vasa deferentia): In men, one of the paired, muscular tubes that travels from the epididymis into the pelvic cavity, to just behind the urinary bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation.

Vasectomy (See Voluntary Surgical Contraception): A permanent sterilization procedure for men. The operation, usually done in a doctor's office, requires cutting and sealing the vas deferens, the tubes in the male reproductive system that carry sperm. A vasectomy prevents the transport of sperm out of the testes.

Vasodilator: An agent that causes dilation of blood vessels.

Vein: A blood vessel that carries blood toward the heart.

Venous plexus: A vascular network formed by numerous connections between veins.

Voluntary surgical contraception: Female and male sterilization (also known as tubectomy, tubal occlusion or tubal ligation, and vasectomy) are among the most effective contraceptive methods available for men and women who desire no more children and are associated with low mortality and complication rates. The sterilization procedure blocks either the sperm ducts (the vasa deferentia) or the oviducts (fallopian or uterine tubes) to prevent the sperm and ovum from uniting.

Vulva: The external female genitals that surround the opening of the vagina and the clitoris.

W

Withdrawal: One of the oldest known methods of contraception in which the man removes his penis from the vagina before ejaculation. Also known as coitus interruptus.

Wet dream: ejaculation of sperm during sleep.