fidelity (n.) Look up fidelity at Dictionary.com
early 15c., "faithfulness, devotion," from Middle French fidélité (15c.), from Latin fidelitatem (nominative fidelitas) "faithfulness, adherence, trustiness," from fidelis "faithful, true, trusty, sincere," from fides "faith" (see faith). From 1530s as "faithful adherence to truth or reality;" specifically of sound reproduction from 1878.