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 many cases, critics frame objections around “historical accuracy” or fidelity to source material, while supporters argue mythology and fiction have always evolved through reinterpretation and artistic adaptation.

From Salon • May 16, 2026

In this case, fidelity refers to the probability that the device gives the correct result when the input is a pure W state.

From Science Daily • May 13, 2026

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

“Sometimes, unconsciously, Daugherty expressed it, with more fidelity to exactness, ‘a great-looking President.’”

From "Blink" by Malcolm Gladwell

Related Words

• devotion
• loyalty