Transmasculine, or transmasc, is an umbrella term for individuals whose gender is partially or fully masculine, and does not correspond with their birth sex/AGAB, or otherwise conform to conventional notions of sex and gender^[1]. This includes trans men, whose gender is masculine in some way.

Transmasculine individuals can also identify as other, non-masculine genders as well. For example, an androgyne individual may identify as transmasculine, though typically, one's masculine identities are more significant than one's non-masculine identities, or one wants to emphasize their masculine identity. Tranmasculine individuals are sometimes called FtM or F2M (female to male); however, this isn't always accurate as not all transmasculine individuals are binary trans men, nor are all transmasc individuals AFAB.

Transmasculine individuals are typically AFAB, though they may also possibly be AXAB or UAB. An AMAB individual may also identify as Transmasculine if their assigned gender or sex is not the same as their gender identity. A simple example of this is an AMAB who identifies as a Demiboy. However a Transmasculine AMAB may also identify as intramasculine and/or admasculine.

Transmasculine is sometimes used, not as a gender identity, but as a way to describe anyone who is assigned female at birth and undergoes masculinization, either through surgery, hormone replacement therapy, or other methods. Under this definition women who take testosterone to attempt to appear more masculine would be considered transmasculine.

The feminine equivalent to transmasculine is transfeminine. The neutral equivalent is transneutral. The androgynous equivalent is transandrogynous. The xenine equivalent is transxenine. The aporine equivalent is transaporine. The outherine equivalent is transoutherine.