Something that must be gained in order to gain something else

“A degree is a prerequisite for entry into this profession.”

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.

“Algebra is typically a prerequisite for physics.”

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

“The prerequisite warm-up to the match was ignored.”