To answer back is to reply rudely to somebody in authority. Do not answer back, he would answer back.
It is said by parents and teachers rather than between equals, since the rudeness is in replying at all. The same words from a colleague would just be disagreement.
1phraseanswer backTo reply rudely to somebody in authority.
“He learnt early not to answer back in that house.”
answer back is a phrase.
Practised in Phrasal Verbs