noun
The uppermost portion
peak, summit, crown, head, crest, tip, apex, cap, crowning point, acme, headpiece, capital, pinnacle, zenith, consummation, spire, knap, finial; see also height 1.
Antonyms bottom*, lower end, nadir.
A cover
lid, roof, ceiling; see cover 1.
A spinning toy
spinner, peg top, whipping top, musical top, whistling top, teetotum, put-and-take top, dreidel; see also toy 1.
*The leader
head, captain, chief, master; see chief 1, leader 2.
blow one's top*
lose one's temper, become angry, be enraged; see rage 1.
off the top of one's head*
on top