seat has 19 distinct synonyms spread across 4 of its 16 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.
any support where you can sit (especially the part of a chair or bench etc. on which you sit)
“he dusted off the seat before sitting down”
a center of authority (as a city from which authority is exercised)
the location (metaphorically speaking) where something is based
“the brain is said to be the seat of reason”
the legal right to sit as a member in a legislative or similar body
“he was elected to a seat in the Senate”
a part of a machine that supports or guides another part
the cloth covering for the buttocks
“the seat of his pants was worn through”
be able to seat
“The theater seats 2,000”
Synonyms, antonyms and the broader and narrower relations for seat come from Princeton University’s WordNet. Full sources and licences.
place or attach firmly in or on a base
“seat the camera on the tripod”
place in or on a seat
“the mother seated the toddler on the high chair”