answer vs plea

answer and plea both are nouns.

Word	Noun	Adjective	Verb	Adverb
answer	Yes	No	Yes	No
plea	Yes	No	No	No

As nouns, plea is a hyponym of answer; that is, plea is a word with a more specific, narrower meaning than answer:

answer: the principal pleading by the defendant in response to plaintiff's complaint; in criminal law it consists of the defendant's plea of `guilty' or `not guilty' (or nolo contendere); in civil law it must contain denials of all allegations in the plaintiff's complaint that the defendant hopes to controvert and it can contain affirmative defenses or counterclaims
plea: (law) a defendant's answer by a factual matter (as distinguished from a demurrer)

Other hyponyms of answer include evasive answer, nolo contendere, non vult.

answer (noun)	plea (noun)
a nonverbal reaction	an answer indicating why a suit should be dismissed
the speech act of replying to a question	a humble request for help from someone in authority
a statement (either spoken or written) that is made to reply to a question or request or criticism or accusation	(law) a defendant's answer by a factual matter (as distinguished from a demurrer)
a statement that solves a problem or explains how to solve the problem
the principal pleading by the defendant in response to plaintiff's complaint; in criminal law it consists of the defendant's plea of `guilty' or `not guilty' (or nolo contendere); in civil law it must contain denials of all allegations in the plaintiff's complaint that the defendant hopes to controvert and it can contain affirmative defenses or counterclaims

answer (verb)	plea (verb)
give the correct answer or solution to
respond to a signal
understand the meaning of
react to a stimulus or command
react verbally
give a defence or refutation of (a charge) or in (an argument)
be satisfactory for; meet the requirements of or serve the purpose of
match or correspond
be liable or accountable
be sufficient; be adequate, either in quality or quantity