Transmasculine refers specifically to an individual that was born and assigned female at birth, but identifies more with masculinity rather than femininity. The term is used generally to refer to any individuals that identify with masculinity over femininity. It is the masculine equivalent of transfeminine.
More About Transmasculine
Transmasculine individuals might include transgendered males that identify with masculinity rather than the typical identity of femininity. Transmasculine can also be used to describe non-binary individuals that consider themselves to be more masculine in a traditional sense. Though an individual might identify with being transmasculine, that does not mean that they will necessarily conform to traditional gender expression or gender roles associated with masculinity.