bit has 17 distinct synonyms spread across 7 of its 11 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a small piece or quantity of something
“a spot of tea”
a unit of measurement of information (from binary + digit); the amount of information in a system having two equiprobable states
“there are 8 bits in a byte”
a short performance that is part of a longer program
“he did his act three times every evening”
the part of a key that enters a lock and lifts the tumblers
the cutting part of a drill; usually pointed and threaded and is replaceable in a brace or bitstock or drill press
“he looked around for the right size bit”
Synonyms, antonyms and the broader and narrower relations for bit come from Princeton University’s WordNet. Full sources and licences.