Verb: When a man inserts himself into a full-blown conversation that had previously involved only women, in order to mansplain something related to the topic they're discussing. Often a reflexive reaction to discourse that would pass the Bechdel Test if it were a movie (because it doesn't involve the man who's overhearing it).
Dude, you just mansplainterrupted a League of Women Voters meeting to tell them about the history of suffrage.
A man whom by virtue of the authority and privilege vested in him by society feels entitled to preach or explain how the world works. Bonus, if he is speaking to women, whom he perceives to be naive and ignorant, about problems and concerns with which women have real life every day experience, and the man has NO fucking clue what he is talking about. This is usually done in a patronizing insensitive manner.
A mansplainer lectures on gynecology, menstruation or gender oppression to women.
Ex. I think women should...
The problem with women today is...
Man trying to mansplain to a women if she came or not during sex.
First described in a Reddit thread about a woman having sex with a guy that tried to argue that she came, even though she clearly didn't and said so to him.