overdrive has 1 distinct synonym spread across 1 of its 4 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 state of high or excessive activity or productivity or concentration
“Troops are ready to go into overdrive as soon as the signal is given”
a high gear used at high speeds to maintain the driving speed with less output power
drive or work too hard
“The teacher is overworking his students”
Synonyms, antonyms and the broader and narrower relations for overdrive come from Princeton University’s WordNet. Full sources and licences.