'Trust' is Old Norse from PIE *deru- (firm as wood) — the same root as 'true,' 'tree,' and 'troth.'
Firm belief in the reliability, truth, ability, or strength of someone or something; confidence placed in a person or thing.
From Old Norse 'traust' meaning 'trust, confidence, protection,' derived from Proto-Germanic *traustą (strong, firm). The word entered English during the Viking Age and displaced the native Old English 'trēowþ' (truth, fidelity) in the sense of 'confidence in another.' The Norse root carried a sense of firmness and solidity