WordNet sense 1 (an indefinitely short time):

minute, moment, second, minute

WordNet sense 2 (a small quantity):

spot

WordNet sense 3 (a small fragment of something broken off from the whole):

chip, flake, fleck, scrap

WordNet sense 4 (a small amount of solid food; a mouthful):

bite, morsel

WordNet sense 5 (an instance of some kind):

piece

WordNet sense 6 (a small fragment):

snatch

WordNet sense 7 (a short theatrical performance that is part of a longer program):

act, number, routine, turn, number