a response to earlier action or activity; opposition to progress or change; (an instance of) a change in one substance caused by another

response

an act of replying; what is replied; answer

answer

an answer (the usual word); reaction

answer, reaction

a quick reply (to an accusation); to answer back quickly, cleverly or angrily (especially to an accusation)

snappy answer

an unkind remark intended to hurt a person's feelings

provocation; teasing