slang for transphobes, short for trans exclusionary radical feminist, although nowadays many terfs are not feminist whatsoever just tend to agree with their transphobic opinions.
I say this because the devs included instructions in the source, that assume the reader is male, several people requested changes to be made to make the language more inclusive, literally just change he to they. the devs refused to do so and instead spend more time defending their position to keep it male centric, than it would take to just make the changes.
you might say, wow that seems like a really simple thing to change and it would make lots of people happy, but instead they would rather alienate perpetual users like me