From Latin 'fidēs' (trust), via Old French — the root behind fidelity, confide, and even federal.
Complete trust or confidence; strong religious belief.
From Old French 'feid,' from Latin 'fidēs' (trust, faith), from 'fīdere' (to trust). Same root gives 'fidelity,' 'confide,' and 'federal.' Key roots: fīdere (Latin: "to trust").