1 hat, head covering:
The plumber took off his cap and scratched his head.
2 lid, top, cover:
3 cap in hand. humbly, meekly, servilely, submissively, subserviently, docilely, respectfully:
He went cap in hand to ask for a pay rise.
4 surpass, outdo, outstrip, better, beat, exceed, top, excel:
Betty capped her earlier triumphs by winning the semifinals.
5 cover, protect:
As it's begun to rain, you'd best cap the camera lens.