A person whose gender (identity) is masculine (but who is not necessarily a man).
In other words, it's a queer space for all men, and women who are trans. Anyone who is read as a cis woman (e.g., lots of trans men and trans mascs) is not welcomed. Grindr has popularized the terms “discreet,” “straight-passing,” and “convincing” within gay culture. 2019, Morgan Lev Edward Holleb, The A-Z of Gender and Sexuality: From Ace to Ze, Jessica Kingsley Publishers, →ISBN, page 140:
Then there's trans men and non-binary mascs, who can change their birth certificates to MALE after breast removal surgery. […] 2018, Quinn Eades, Son Vivienne, Going Postal: More than 'Yes' or 'No': One year on: writings from the marriage equality postal survey, Brow Books, →ISBN: