adaptation has 3 distinct synonyms spread across 2 of its 3 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 written work (as a novel) that has been recast in a new form
“the play is an adaptation of a short novel”
the process of adapting to something (such as environmental conditions)
(physiology) the responsive adjustment of a sense organ (as the eye) to varying conditions (as of light)
Synonyms, antonyms and the broader and narrower relations for adaptation come from Princeton University’s WordNet. Full sources and licences.