In general in communication an answer is a response. E.g., an answer is the response to a question, hopefully to satisify the questioner. The answer to the great question is also known as the theory of everything. It can also be a response to a telephone, letter, front door, etc.
The Answer establishes which allegations (cause of action in civil matters) set forth by the complaining party will be contested by the defendant, and states all the defendant's defenses, thus establishing the nature and parameters of the controversy to be decided by the court.
In the case of a criminal case there is usually an arraignment or some other kind of appearance before the court by the defendant. The pleading in the criminal case, which is entered on the record in open court, is either guilty or not guilty. Generally speaking in private, civil cases there is no guilt or innocence. There is only a judgment that grants money damages or some other kind of equitable remedy such as restitution or an injunction. Criminal cases may lead to fines or other punishment, such as imprisonment.
Someone to whom you are answerable is one who looks after you, or someone who gives you rules which you must comply with.
