Butch is an LGBTQ+ masculine gender expression or gender identity. While many people who identify as butch use the term in reference to their gender expression, others claim it as a nonbinary identity in itself, notably Leslie Feinberg, who defined butch as a gender neither male nor female. Butch is an identity that emerged in lesbian and bisexual culture in the 1940s, before there was a stark distinction in the community between types of women who were attracted to other women. Many lesbians have complicated relationships with gender, and may identify as simply butch. Butch is an identity that can be held by people of various queer sexual orientations and can belong to both cisgender and trans individuals.

Traditionally, the identity and term butch has been used by individuals who are attracted to femmes. For some butches, this attraction to femmes represents a strong part of their own identity. Because of this, you will often see the dyadic term "butch/femme," or referrals to a butch/femme dynamic. However, some butches are attracted to other butches (this was already a topic in Leslie Feinberg's seminal novel Stone Butch Blues). The phenomenon of butches attracted to other butches is commonly called "masc-for-masc".

Depending on the community in question, butch people may call themselves by different terms. In Black and Latine communities, there may be a preference for the words aggressive (ag for short) or stud, with much the same meaning as butch.[2][3] White people should use "butch" or another term rather than "stud".

International Butch Appreciation Day is celebrated on August 18 annually.