something said or written after a question, request, a letter asking for something etc

reply; reaction

an obvious refusal to obey

disobedience, disregard

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

response

the state of being disobedient

defiance

a comment or opinion; to say something (which is more usual)

comment, observation

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