Real Dictionary

high fidelity
High fidelity is the use of electronic equipment to reproduce a sound or image with very little distortion or loss of quality.
noun: the reproduction of sound using electronic equipment that gives faithful reproduction with little or no distortion

high-fidelity in British English
in radio, sound recording, etc., an approximately exact reproduction of sound achieved by low distortion and a wide range of reproduced frequencies, from approximately 20 to 20,000 hertz
modifier: of or relating to high fidelity equipment or sound
noun: sound reproduction over the full range of audible frequencies with very little distortion of the original signal