deviation has 9 distinct synonyms spread across 3 of its 5 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 variation that deviates from the standard or norm
“the deviation from the mean”
the difference between an observed value and the expected value of a variable or function
the error of a compass due to local magnetic disturbances
a turning aside (of your course or attention or concern)
“a diversion from the main highway”
Synonyms, antonyms and the broader and narrower relations for deviation come from Princeton University’s WordNet. Full sources and licences.