early 15c., altered from presupponen (c. 1400), "assume beforehand or in the beginning," from Old French presupposer (14c.), formed in French or else from Medieval Latin praesupponere; see pre- + suppose. The meaning "take for granted in advance of actual knowledge or experience" is from 1520s. Related: Presupposed; presupposing.
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.
Proto-Indo-European root meaning "under," also "up from under," hence "over."
It forms all or part of: above; assume; Aufklarung; eave; eavesdropper; hyphen; hypo-; hypochondria; hypocrisy; hypotenuse; hypothalamus; hypothesis; hypsi-; hypso-; opal; open; oft; often; resuscitate; somber; souffle; source; soutane; souvenir; sub-; subject; sublime; subpoena; substance; subterfuge; subtle; suburb; succeed; succinct; succor; succubus; succumb; sudden; suffer; sufficient; suffix; suffrage; suggestion; summon; supine; supple; supply; support; suppose; surge; suspect; suspend; sustain; up; up-; Upanishad; uproar; valet; varlet; vassal.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit upa "near, under, up to, on," Greek hypo "under," Latin sub "under, below," Gothic iup, Old Norse, Old English upp "up, upward," Hittite up-zi "rises."
slang shortening, I suppose, of credit, credibility or credentials; by 1992.