Menstruation is something just about all healthy preteen to midlife women experience nearly every month. But even though you’re intimately familiar with your period, you may not know the language used to describe its process, products, and problems. This glossary of menstrual terms will help.

Amenorrhea The absence of first menstrual period by age 15; secondary amenorrhea refers to a stretch of at least three months without menstruation, whether from pregnancy or from a medical condition.

Cramps Throbbing or cramping pain (hence the name) in the lower abdomen brought on by your period. They can be mildly uncomfortable or so severe they make you vomit.

Dysmenorrhea Painful periods. Doctors call it primary dysmenorrhea (the most common type) if it isn’t caused by another condition, and secondary dysmenorrhea if it is (due to endometriosis, for example).

Endometriosis A disease in which tissue similar to the uterine lining (endometrium) grows outside the lining of the uterus.

Feminine Hygiene Products The euphemistic term for products used by women in and around their vagina. For periods, these include sanitary napkins, pads, tampons, menstrual cups, and the like. The phrase can also refer to vaginal douches, which doctors say you should not use, according to the U.S. Department of Health and Human Services (HHS).

Follicular Phase The first half of your monthly cycle. During this phase the follicles (eggs) in your ovaries mature and one (or more) is released into the fallopian tube.

Free Bleeding Forgoing feminine hygiene products during your period. While some women are forced to free bleed because they don’t have access to or money to buy products, in developed countries it may be practiced as a way to normalize menstruation and remove any embarrassment surrounding this natural female bodily process.

Luteal Phase The second half of your monthly cycle. During this phase, the lining of your uterus thickens in anticipation of a pregnancy. This phase ends either in pregnancy or menstruation.

Menarche The technical term for the first time you menstruate.

Menopause The time in life after you have not had a period for at least one year. The average age of menopause in the United States is 52, according to the HHS, although the range is quite large. Women who have their ovaries surgically removed instantly go into menopause.

Menorrhagia A condition in which your periods are abnormally heavy or prolonged. The loss of so much blood can lead to anemia, or iron-deficiency, and so should be discussed with a physician.

Menses Another word for menstruation. Sometimes the term “menses” describes the blood rather than the entire process.

Menstrual Cup This small, flexible device made from latex or rubber is inserted into the vagina to catch menstrual blood. Blood is eventually dumped out and the device reinserted. Because it is reusable, it is considered an environmentally friendly form of feminine hygiene.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) A class of drugs typically used to control period pain. NSAIDs include ibuprofen (Motrin, Advil), naproxen (Aleve, Naprelan), and aspirin.

Ovulation The release of an egg from an ovary. After ovulation the egg is available to be fertilized by sperm to produce a pregnancy if no birth control methods are used.

Perimenopause The years leading up to menopause when hormones begin to fluctuate. Women often experience symptoms such as hot flashes and night sweats during perimenopause.

Period Panties This modern invention is underwear that can be worn during menstruation instead of, or along with, other menstrual products. The panties are designed to absorb blood and are washable after wearing.

Period Poverty Lacking finances to buy tampons, sanitary pads, menstrual cups, or other products to contain menstrual blood. Period poverty exists in the United States as well as in underdeveloped countries.

Polycystic Ovary Syndrome (PCOS) A hormonal disorder that can affect your period, cause the release of too much male hormone (androgen), and lead to infertility. The name comes from small collections of cyst-like fluids on the ovaries.

Premenstrual Dysphoric Disorder (PMDD) The most severe form of premenstrual syndrome (PMS). In addition to physical pain and mood changes, people with PMDD may also suffer extreme emotional symptoms, such as sadness, anxiety, or anger.

Premenstrual Syndrome (PMS) A common condition that appears up to 10 days before your period and continues into the first few days of bleeding. Symptoms can be physical (headache, fatigue, bloating) or emotional (anxiety, irritability, insomnia), and can range from relatively mild to fairly severe.

Prostaglandins These hormone-like substances in the body are responsible for smooth-muscle (think uterus) contractions, quelling inflammation, and more. Prostaglandins are believed to play a role in menstrual cramps. NSAID drugs work in part by lessening the effects of prostaglandins.

Puberty The time in a person’s life when sex hormones begin to affect their sexual development. In girls, this results in breast development, change in body shape, and onset of fertility.

Spotting Light vaginal bleeding between periods. Spotting can be natural or caused by a disease. Wearing a light sanitary pad is usually sufficient to catch the small amount of blood involved.

Tampon A menstrual product made of rayon or cotton (or a combination) that is inserted into the vagina. Tampons expand and catch blood before it has a chance to leave the body. They may come with an applicator, or you may use your fingers to insert. Tugging on the string at the end of the tampon removes it.

Uterus The part of a woman’s body where period blood develops. The uterus is a hollow organ located in the pelvis, above the vagina. Blood lining the walls of the uterus each month in preparation for receiving a fertilized egg is shed as your period if you don’t become pregnant.

Uterine Fibroids Growths in the uterus that are not cancerous. Also called leiomyoma, they can range in size from tiny specks to bulky masses that can cause pain and prevent pregnancy. Uterine fibroids may affect your period’s flow and the cramps you experience.

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