To explain to a
person with condescension. To assume you are more qualified to speak on a subject than a trained professional because of something you read on the
Internet, or in a book, etc; or because of an assumption based on
gender. (Including man/womansplaining).
Can be used as an umbrella or gender neutral term.
The antivaxxer condesplained to the
doctor the dangers of the MMR vaccine based on a debunked
paper.
Judy knew that men didn't know how to
cook so she proceeded to condesplain a simple recipe to her coworker.