pressure has 16 distinct synonyms spread across 7 of its 9 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.
the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)
“the compressed gas exerts an increased pressure”
a force that compels
“the public brought pressure to bear on the government”
the act of pressing; the exertion of pressure
“he gave the button a press”
the somatic sensation that results from applying force to an area of skin
“the sensitivity of his skin to pressure and temperature was normal”
an oppressive condition of physical or mental or social or economic distress
to cause to do through pressure or necessity, by physical, moral or intellectual means
“She forced him to take a job in the city”
Synonyms, antonyms and the broader and narrower relations for pressure come from Princeton University’s WordNet. Full sources and licences.