mansplain
To explain in a condescending, oversimplified, and often inaccurate manner, without regard to the fact that the explainee knows more than the explainer, usually done by a man to a woman.

Not all condescending explanations are mansplaining; the term does not apply when the man in question is indeed more knowledgeable about the topic than the woman.

Mansplaining usually occurs on the topic of sexism, feminism, or gender inequality, but not always. For example, a male programmer could mansplain coding to a woman, despite the woman having more qualifications and writing better-quality code.

Related terms include whitesplain, straightsplain, and cisplain. The overarching thread is someone privileged explaining something to someone less privileged, about a topic the explainer knows less about.
A: “Stop mansplaining. You have no idea what it feels like to be subjected to sexism.”
B: “Feminists are ridiculous! Mansplaining is when a man’s point is discredited just because he’s male, not because he’s wrong!”
A: “What the hell, did you just mansplain mansplaining to me?”