To spend time sitting idly, not doing anything important.

(idiomatic) To unwillingly stay seated until the end of an event.

To recline while still in a seated position, with one's back on the frame of the seat. / (idiomatic) To relax, to not exert oneself.

(idiomatic, intransitive) To remain neutral on a certain topic, to not have a stance or opinion.

A nonviolent protester who participates in a sit-in.

plural of sitting duck

present participle of sit out

present participle of sit down

present participle of sit up

plural of sit-inner