Pronunciation: (fi-del'i-tE, fI-), [key] —n., —pl.-ties. 1. strict observance of promises, duties, etc.: a servant's fidelity. 2. loyalty: fidelity to one's country. 3. conjugal faithfulness. 4. adherence to fact or detail. 5. accuracy; exactness: The speech was transcribed with great fidelity. 6. Audio.,Video.the degree of accuracy with which sound or images are recorded or reproduced.