A term created by radical feminists to automatically discredit the opinion of a man because he's, well, a man. See also Feminist Shaming Language.
Man: I think your argument about women being oppressed by an evil patriarchy is wrong because of x, y and z.
Feminist group: Oh look, mansplaining from a member of the male species! How dare you interrupt our bitching session with your facts and logic! Let's get him, sisters! Make jokes about him having a small penis, that'll show him!
The tendency of some men to mistakenly believe that they automatically know more about any given topic than does a woman and who, consequently, proceed to explain to her- correctly or not- things that she already knows.
Woman A: When he started mansplaining to me what it really meant to be a woman in the 21st century, I got up and left.
Woman B: Really, what else could you do?
A sexist term used by misandrist women to disrespect, belittle and devalue the opinion of her male peers in an attempt to make herself appear smarter or better in comparison.
This is common among mixed gender discussions and debates. The term mansplaining is commonly thrown around by those wish to turn the argument into a battle of the sexes or just lack any knowledge or means od adding value to the discussion and wish to devalue the input of other's (in this case males) who are involved in said discussion.
Sue: "I think WWII was hardest on wives back home then the solders."
Bob: "What about the men serving who put their lives at risk during WWII? I think it was harder on them knowing they might die and not see their wife again."
Sue: "Oh there you go again mansplaining!"
A word used by pseudo-intellectual feminist (e.g. ugly chicks, over 30 single moms with no chance in hell of getting a man their own age, and insecure fat chicks or combo of all three) on the internet to justify their loosing argument and/or anti-male rhetoric.
Man: "Hey, I found new talk show on YouTube that's cool check it out"
Pseudo-intellectual feminist: FUCK THAT GUY WITH A RUSTY CHAIN SAW HE'S A MISOGYNIST.
Man: Oh really? I didn't know that about the guest, but um...I was talking about the show in general and the Host.
Pseudo-intellectual feminist: THANKS FOR MANSPLAINING.
Originally, this term was used to describe boorish men who felt the need to "correct" what a woman said, even on topics that the man didn't know anything about.
However, the term quickly degenerated into a get-out-of-jail-free card used by angry women when a man dares to point out even the most blatant error.
Old: That Bob is trying to tell Jill how to raise a horse? She's raised championship thoroughbreds for decades and he's never even ridden a horse. What a stupid mansplainer!
New: OF COURSE HAMSTERS KNOW HOW TO SPEAK IN RUSSIAN! STOP MANSPLAINING!