response has 4 distinct synonyms spread across 4 of its 7 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 result
“this situation developed in response to events in Africa”
a bodily process occurring due to the effect of some antecedent stimulus or agent
“a bad reaction to the medicine”
a phrase recited or sung by the congregation following a versicle by the priest or minister
the speech act of continuing a conversational exchange
“he growled his reply”
the manner in which an electrical or mechanical device responds to an input signal or a range of input signals
Synonyms, antonyms and the broader and narrower relations for response come from Princeton University’s WordNet. Full sources and licences.