faith [ME] Both faith and fidelity [LME] come from the Latin word fides. Fido, a traditional name for a dog, is also related—it represents the Latin for ‘I trust’. Other words from the same source include confidence [LME], confide [LME], and diffident [LME] which originally meant ‘lacking in trust’. Fiancé(e), the French for ‘promised’, which goes back to fides, is related. See also infidel.