Wiktionary
vb. 1 To remain motionless. 2 (context idiomatic English) To accept, tolerate, or acquiesce.
Usage examples of "sit still".
Too excited to sit still, the major stood with his back against the door, as alert as if he were about to turn and face the enemy.
That small, quick boy, as unable to be quiet as he was to sit still, could seemingly talk for hours about a half dozen raindrops, and his words tumbled out breathlessly as he fidgeted.
He had managed to get by in school because he found the work easy, but he had been forever bedeviling his teachers with his inability to sit still.
Ann Eliza was glad to sit still: the baby's petticoat that she was stitching shook in her fingers.
The Sangaree would not sit still for a billion-stellar burn from God Himself.
Nevertheless, short of resorting to Discipline, Varian found it nauseatingly irksome to sit still in a comfortable chair through a Thek relay.