Transmasculine
Moving towards masculinity from a female assignment at birth.
Transmasculine covers people assigned female at birth whose gender sits towards the masculine end — trans men, but also masculine non-binary people who don't identify as men.
It's deliberately broader than trans man. Someone might be transmasc and non-binary, transmasc and agender, or transmasc while still working out the rest. The word makes room for that.
It says nothing about medical transition. Transmasc people take testosterone or don't, have surgery or don't, and remain transmasc either way.