presupposition (n.)

1530s, "surmise, conjecture, supposition antecedent to knowledge," from French présupposition and directly from Medieval Latin praesuppositionem (nominative praesuppositio), noun of action from past-participle stem of Latin praesupponere, from prae "before" (see pre-) + suppositio (see suppose). Meaning "postulation as of an antecedent condition," hence "a prerequisite" is from 1570s.