prerequisite

Required or necessary as a prior condition.

Something that is prerequisite, as a course that is required prior to taking an advanced course.

Previously required; necessary as a condition of something following.

A condition required beforehand; a preliminary necessity.

Previously required; necessary as a preliminary to any proposed effect or end.

Something previously required, or necessary to an end or effect proposed.

Required as a prior condition of something else; necessary or indispensable.

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.

something that is required in advance