(idiomatic) To clearly understand one's own feelings, intentions, preferences, etc; to know precisely what one wants; to be decisive or determined.

Third-person singular simple present indicative form of know someone in the biblical sense

(idiomatic) To have sex with someone.

(intransitive, idiomatic) To be experienced and knowledgeable. / (transitive, idiomatic) To be very familiar with; to have a significant understanding of.

Alternative form of know which end is up

(idiomatic) To possess sound judgment or common sense; to have a clear understanding of a situation.

(figuratively) To be aware of one's position.

(informal) To understand one's situation, how to act in that situation, and the results of those actions.

Alternative form of better the devil you know than the devil you don't know

Synonym of know what one is about