introduce has 17 distinct synonyms spread across 8 of its 10 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.
cause to come to know personally
“permit me to acquaint you with my son”
bring before the public for the first time, as of an actor, song, etc.
put before (a body)
“introduce legislation”
be a precursor of
“The fall of the Berlin Wall ushered in the post-Cold War period”
Synonyms, antonyms and the broader and narrower relations for introduce come from Princeton University’s WordNet. Full sources and licences.