fidelity

American  

[fi-del-i-tee, fahy-] / fɪˈdɛl ɪ ti, faɪ- /

noun

plural

fidelities

1. strict observance of promises, duties, etc..

   a servant's fidelity.

2. loyalty.

   fidelity to one's country.

   Antonyms:

   disloyalty

3. conjugal faithfulness.

4. adherence to fact or detail.

5. accuracy; exactness.

   The speech was transcribed with great fidelity.

   Synonyms:

   rigor, faithfulness, precision

6. Audio, Video. the degree of accuracy with which sound or images are recorded or reproduced.

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fidelity British  

/ fɪˈdɛlɪtɪ /

noun

1. devotion to duties, obligations, etc; faithfulness

2. loyalty or devotion, as to a person or cause

3. faithfulness to one's spouse, lover, etc

4. adherence to truth; accuracy in reporting detail

5. electronics the degree to which the output of a system, such as an amplifier or radio, accurately reproduces the characteristics of the input signal See also high fidelity

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Related Words

See loyalty.

Other Word Forms

• nonfidelity noun
• unfidelity noun

Etymology

Origin of fidelity

First recorded in 1500–10; late Middle English fidelite (from Middle French ), from Latin fidēlitās, equivalent to fidēli- (stem of fidēlis “loyal,” equivalent to fidē(s) faith + -lis adjective suffix) + -tās -ty ²

Explanation

Fidelity is the quality of being faithful or loyal. Dogs are famous for their fidelity. Fidelity comes from the Latin root fides, which means faith, so fidelity is the state of being faithful. Marital fidelity is faithfulness to your spouse. If you're a journalist, your reports should have fidelity to the facts. Someone without fidelity to a religion or group belief is called an infidel.

Example Sentences

In 2024, privately held Quantinuum became the first in the industry to achieve the milestone, with IonQ subsequently crossing the “four nines” threshold with the achievement of 99.99% fidelity in October.

From Barron's • Apr. 21, 2026

In the West Bengal election, fish has slipped from the plate into the centre of the campaign, recast as proof of cultural fidelity and a rebuttal to charges of intrusion.

From BBC • Apr. 20, 2026

“Black Bag” tore up spy movie conventions with its emphasis on fidelity in the field, becoming one of the genre’s most scintillating new films in years.

From Salon • Apr. 17, 2026

How do you get it there with better fidelity and a lower cost?

From The Wall Street Journal • Mar. 28, 2026

Both accepted the call out of a combination of fidelity to Lawrence and duty to country—the latter communicated to them also by Lawrence, who emphasized that their work would be crucial to the war effort.

From "Big Science" by Michael Hiltzik

Related Words

• devotion
• loyalty