Prerequisite
Part of speech: adjective
Definition: required as a prior condition of something else; necessary or indispensable
Part of speech: noun
Definition: Something that must be gained in order to gain something else In education, a course or topic that must be completed before another course or topic can be started. May be colloquially referred to as a prereq.
Example sentence: When the Australian Government looked at how to meet the challenges, and the opportunities, presented by our ageing population, it saw that an all-encompassing approach was a prerequisite.
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.
Example sentence: Perhaps no place in any community is so totally democratic as the town library. The only entrance requirement is interest.