When a mathematically capable person explains a math problem to a less mathematically capable person, typically in a manner regarded as condescending or patronising. Like mansplaining, except that it actually exists.
Math HL student: "Uh, you can't get the square root out of a negative number. Unless you're using irrationals"
Math studies student: "Stop mathsplaining to me!"
Math studies student: "Stop mathsplaining to me!"
by FanterPanter December 7, 2017