shower has 7 distinct synonyms spread across 6 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 plumbing fixture that sprays water over you
“they installed a shower in the bathroom”
washing yourself by standing upright under water sprayed from a nozzle
“he took a shower after the game”
Synonyms, antonyms and the broader and narrower relations for shower come from Princeton University’s WordNet. Full sources and licences.
a brief period of precipitation
“the game was interrupted by a brief shower”
someone who organizes an exhibit for others to see
a party of friends assembled to present gifts (usually of a specified kind) to a person
“her friends organized a baby shower for her when she was expecting”
spray or sprinkle with
“The guests showered rice on the couple”
take a shower; wash one's body in the shower
“You should shower after vigorous exercise”
provide abundantly with
“He showered her with presents”