B.

Basal Body Temperature - One's body temperature in the morning before rising or moving about or eating anything. Some people use this to track ovulation, as a fertility awareness method.

Being Read - An alternative phrase to passing that shifts responsibility of correct gendering onto onlookers, instead of on the person who is read. A trans person who is read correctly is recognized as their correct gender.

Bigender - A person whose sense of personal identity encompasses two genders.

Binder - A garment used mainly by trans-masculine people to compress their breasts to give the appearance of having a flat chest.

Binarism -
1. The belief, prejudice or social force that claims only two genders exist, male and female, and that all nonbinary and genderqueer gender identities are invalid.
2. The erasing or antagonizing of people whose genders are outside of the gender binary in indigenous and colonized cultures.
Binary Gender - A gender that is either strictly male or strictly female. This is not affected by whether a person is cis or trans: a trans man or trans woman has a binary gender, unless he or she also identifies as nonbinary.

Biological Essentialism - In trans discussions, the belief that a person’s gender can only be defined by their genes and/or genitalia at birth. Biological essentialism usually ignores the existence of intersex people and is a major component of transphobia.

Bioidentical Hormone - Substances with the identical chemical structure of natural hormones produced by the body. These are produced in a lab.

Biological Sex -
1. A social construct that categorizes human bodies as male or female based on chromosomes or genitalia. Contrary to popular belief, there are not two biological sexes, because people can be born with a wide variety of sexual characteristics, and many different combinations of sexual characteristics. Many trans people find the phrase or concept offensive, and prefer the phrase “assigned sex,” or “designated sex.”
2. A medical term referring to one's personal combination of gonads, chromosomes, external organs, secondary sex characteristics and hormonal balances. Typically, this is used to refer to that what which one is born with, however several of these traits can be changed through the usage of hormones, and undergoing surgery.
Body Dysmorphic Disorder - A mental disorder in which someone is excessively preoccupied with some aspect of their appearance, to the point of causing severe anxiety or depression. It should not be confused with gender dysphoria, although the symptoms may be superficially similar.

Body Dysphoria - A feeling of stress or unhappiness related to one’s body. In trans discussions, it is a type of gender dysphoria caused by the body’s appearance clashing with one’s internal gender identity.

Bottom Surgery - A colloquial term for surgery that corrects one’s genitalia to better match one’s gender.

Boy Mode - Appearing to the world as a boy or man, regardless of one's true gender.

Bra - A bra is an undergarment that is worn for the purpose of securing, enhancing, and embracing a set of breasts.

Brain Sex - A controversial idea that posits that a person’s gender identity may be reflected by the structure of their brain.

Breast Augmentation - Cosmetic procedure to increase the size of breasts, typically with silicone or saline implants.

Breast Forms - Artificial breasts, mainly used by trans-feminine people, to give the appearance of having breasts.

Butch - More reminiscent of what is traditionally considered boyish or masculine than feminine. May refer to a gender identity, gender presentation, or a style of dress. Strongly associated with lesbian culture.