Requirement
Part of speech: noun
Definition: A necessity or prerequisite; something required or obligatory. Something asked. (engineering) A statement (in domain specific terms) which specifies a verifiable constraint on an implementation that it shall undeniably meet or (a) be deemed unacceptable, or (b) result in implementation failure, or (c) result in system failure.
Demand
Part of speech: verb
Definition: To request forcefully.To claim a right to something.To ask forcefully for information.To require of someone.To issue a summons to court.
Part of speech: noun
Definition: The desire to purchase goods and services.The amount of a good or service that a consumer is willing to buy at a particular price.A need.A claim for something.A requirement.An urgent request.An order.(electric) the measure of the maximum power load of a utility's customer over a short period of time; the power load integrated over a specified time interval.