answer

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A spoken or written reply, as to a question.
• noun A correct reply.
• noun A solution, as to a problem.
• noun A correct solution.
• noun An act in response or retaliation.
• noun Something markedly similar to another of the same class.
• noun Law A defendant's response to the allegations against him or her.
• intransitive verb To speak or write as a return, as to a question.
• intransitive verb To act in response.
• intransitive verb To be liable or accountable.
• intransitive verb To serve the purpose; suffice.
• intransitive verb To correspond; match.
• intransitive verb To speak or write in response to.
• intransitive verb To say or write in reply.
• intransitive verb To argue in defense of oneself against (an accusation or charge).
• intransitive verb To act in response to.
• intransitive verb To be sufficient for (a need, for instance); fulfill.
• intransitive verb To conform or correspond to.

from The Century Dictionary.

• To make answer; speak or write in reply to a question (expressed or implied), request, appeal, petition, prayer, call, demand, challenge, address, argument, letter, or anything said or written; reply; respond: used with to, or absolutely.
• In particular— To reply to a charge or an accusation; make a statement in defense or justification of one's self, with regard to a charge or an accusation; specifically, in law, to interpose a pleading responsive to plaintiff's allegations of fact: sometimes used to include also the interposing of a demurrer: formerly sometimes with with.
• To give a solution of a problem; find the result; give an answer, as to a question set for examination: as, he answered correctly in most instances.
• To reply or respond in act; act or move in response; do something in return for or in consequence of some speech, act, or movement from another source.
• To speak in behalf of another; declare one's self responsible or accountable, or give assurance or guaranty, for another; be responsible or accountable: used with for, rarely absolutely: as, I will answer for his safety; I am satisfied, but I cannot answer for my partner.
• To act or suffer in consequence of responsibility; meet the consequences: with for, rarely absolutely.
• To meet, satisfy, or fulfil one's wishes, expectations, or requirements; be of service: with for; absolutely, to serve the purpose; attain the end; suit; serve or do (well or ill, etc.).
• To conform, correspond; be similar, equivalent, proportionate, or correlative in character, quality, or condition: with to.
• To make answer to; speak or write in reply to; reply or respond to.
• In particular— To reply to a charge or an accusation by; make a statement to, or in reply to, in defense or justification of one's self with regard to a charge or an accusation.
• To solve; find the result of; give an answer to, as to a question set for examination: as, he answered every question.
• To say or offer in reply, or in reply to; utter, or enunciate to, by way of response.
• To reply or respond to in act; act or move in response to or in consequence of: either as a mere result, in obedience to or sympathy with, or as a hostile act in retaliation or reprisal against: as, to answer prayer; to answer a summons; to answer a signal, as a ring at the door: hence, to answer the bell, or the door; to answer the helm (said of a ship when she obeys her rudder).
• To be responsible for; be accountable for.
• To act or suffer in consequence of responsibility for; meet the consequences of; atone for; make amends for; make satisfaction for.
• To meet, satisfy, or fulfil one's wishes, expectations, or requirements with regard to; satisfy (a claim); repay (an expense); serve (the purpose); accomplish (the end); serve; suit.
• To conform to; correspond to; be similar, equivalent, proportionate, or correlative to in quality, attributes, position, etc.
• To meet or confront.
• noun A reply, response, or rejoinder, spoken or written, to a question (expressed or implied), request, appeal, prayer, call, petition, demand, challenge, objection, argument, address, letter, or to anything said or written.
• noun In particular— A reply to a charge or an accusation; a statement made in defense or justification of one's self, with regard to a charge or an accusation; a defense; specifically, in law, a pleading on the part of the defendant, responding to the plaintiff's claim on questions of fact: correlative to demurrer, which raises only questions of law. The word as used in equity nearly, and as used in recent codes of procedure closely, corresponds to the common-law plea.
• noun The solution of a problem; the result of a mathematical operation; a statement made in response to a question set for examination: implying correctness, unless qualified.
• noun A reply or response in act; an act or motion in return or in consequence, either as a mere result due to obedience, consent, or sympathy, or as a hostile procedure in retaliation or reprisal.
• noun Specifically— In fencing, the return hit.
• noun In fugue-music, the enunciation of the subject or theme by the second voice.
• noun Often abbreviated to ans. and adjective

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To speak in defense against; to reply to in defense
• transitive verb To speak or write in return to, as in return to a call or question, or to a speech, declaration, argument, or the like; to reply to (a question, remark, etc.); to respond to.
• transitive verb To respond to satisfactorily; to meet successfully by way of explanation, argument, or justification, and the like; to refute.
• transitive verb To be or act in return or response to.