air has 25 distinct synonyms spread across 10 of its 15 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 mixture of gases (especially oxygen) required for breathing; the stuff that the wind consists of
“air pollution”
the region above the ground
“her hand stopped in mid air”
a slight wind (usually refreshing)
“the breeze was cooled by the lake”
the mass of air surrounding the Earth
“there was great heat as the comet entered the atmosphere”
once thought to be one of four elements composing the universe (Empedocles)
a succession of notes forming a distinctive sequence
“she was humming an air from Beethoven”
be broadcast
“This show will air Saturdays at 2 P.M.”
Synonyms, antonyms and the broader and narrower relations for air come from Princeton University’s WordNet. Full sources and licences.
broadcast over the airwaves, as in radio or television
“We cannot air this X-rated song”
expose to warm or heated air, so as to dry
“Air linen”