pet has 11 distinct synonyms spread across 3 of its 7 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 domesticated animal kept for companionship or amusement
a fit of petulance or sulkiness (especially at what is felt to be a slight)
using a computerized radiographic technique to examine the metabolic activity in various tissues (especially in the brain)
stroke or caress in an erotic manner, as during lovemaking
Synonyms, antonyms and the broader and narrower relations for pet come from Princeton University’s WordNet. Full sources and licences.