c.1200, from O.N. traust "help, confidence," from P.Gmc. *traust- (cf. O.Fris. trast, Du. troost "comfort, consolation," O.H.G. trost "trust, fidelity," Ger. Trost "comfort, consolation," Goth. trausti "agreement, alliance"). Related to O.E. treowian "to believe, trust," and treowe "faithful, trusty" (see true). Meaning "businesses organized to reduce competition" is recorded from 1877. The verb (c.1225) is from O.N. treysta "to trust." Trust-buster is recorded from 1903. Trustee in the sense of "person who is responsible for the property of another" is attested from 1653. Trustworthy is first attested 1808.
Etymology: Middle English, probably of Scandinavian origin; akin to Old Norse traust trust; akin to Old English trēowe faithful — more at true
Date: 13th century
1 a: assured reliance on the character, ability, strength, or truth of someone or something b: one in which confidence is placed
— in trust: in the care or possession of a trustee