fidelity

fidelity — noun

1. a state of faithful dedication to a person, group, or belief, especially within

1.nounB2
Definition

a state of faithful dedication to a person, group, or belief, especially within a romantic relationship where both partners expect honesty and commitment.

Example

Padma valued fidelity in her marriage above everything else.

collocation: fidelity in marriage

The knight's fidelity to the crown was never questioned.

passive: fidelity to [institution] was never questioned

Common collocations
  • marital fidelity
  • sexual fidelity
  • pledge fidelity
  • fidelity to a partner
  • fidelity to a cause
Synonyms
  • loyalty

    more general; can apply to countries, teams, brands, whereas 'fidelity' often implies a deeper personal bond

  • faithfulness

    very close in meaning; 'faithfulness' sounds slightly more emotional, 'fidelity' more formal

  • allegiance

    chiefly used for loyalty to a country, government, or leader — less personal than 'fidelity'

Antonyms
  • infidelity

    the direct opposite; specifically for sexual unfaithfulness in a relationship

  • disloyalty

    broader; covers betrayal of any person, group, or cause

Grammar Patterns

fidelity + to

Usage Note

Frequently paired with the preposition 'to' (fidelity to someone/something). The adjective 'faithful' is more common in everyday speech; 'fidelity' is noticeably more formal.

Common Mistakes

She showed fidelity for her husband.
She showed fidelity to her husband.
The correct preposition after 'fidelity' is 'to', not 'for'.
His fidelity was unwavering toward the company.
His fidelity to the company was unwavering.
Keep 'fidelity' and the preposition close together in the sentence.

2. the extent to which a copy or reproduction of something — such as a sound record

2.nounB2
Definition

the extent to which a copy or reproduction of something — such as a sound recording, image, or piece of information — matches the original in detail and quality.

Example

The new speakers offer excellent sound fidelity across all frequencies.

collocation: sound fidelity

Zuri was impressed by the high fidelity of the digital scan.

Common collocations
  • sound fidelity
  • audio fidelity
  • image fidelity
  • data fidelity
  • colour fidelity
  • high fidelity
  • low fidelity
Synonyms
  • accuracy

    broader; can apply to any situation requiring correctness, not just reproduction

  • precision

    focuses on exactness of detail; more common in measurements than in audio/visual contexts

  • authenticity

    emphasises being genuine rather than a mere copy; closer to 'realness' than 'accuracy'

Antonyms
  • distortion

    a change that makes a reproduction inaccurate, especially in sound or image

  • inaccuracy

    general lack of correctness; less specific to reproduction

Grammar Patterns

fidelity + of

adjective + fidelity

fidelity + to

Usage Note

Commonly modified by adjectives such as 'high', 'low', 'excellent', 'remarkable'. The fixed phrase 'high fidelity' ('hi-fi') is a standard term for high-quality audio equipment. Often used in technical writing about audio, video, imaging, and data.

Common Mistakes

The sound system has good fidelity of sound.
The sound system has good sound fidelity.
Use 'fidelity' as a noun modifier ('sound fidelity'), not with the preposition 'of' following it.

Word family

  • faithful
    adjectiveB1
  • faithfully
    adverbB1
  • infidelity
    nounC1
  • unfaithful
    adjectiveB2
  • fidelities
    nounC2

Synonym discussion

Sense: noun/1

Fidelity, loyalty, faithfulness, and allegiance all describe some form of commitment, but differ in scope and context. Fidelity is the most formal of the group and carries a strong undertone of honour — it is the quality of being true to a promise or duty, especially in marriage or to a cause. Loyalty is broader; you can feel loyalty to a brand, a sports team, or a friend, and it can be based on habit or affection rather than a formal vow. Faithfulness overlaps closely with fidelity but sounds warmer and more emotional — it is often used in personal relationships ('a faithful husband') rather than institutional ones. Allegiance is the most political; it refers to loyalty to a government, ruler, or nation (as in 'swearing allegiance to the flag'). In everyday conversation, 'loyalty' is the most flexible choice — you can use it almost anywhere. 'Fidelity' is best saved for formal writing or contexts that emphasise keeping a specific promise.

fidelity ↗loyalty ↗faithfulnessallegiance ↗

Common collocations

Phrases

  • high fidelity
  • low fidelity

Prepositions

  • fidelity to
  • fidelity of
  • fidelity in

Etymology

LatinFrenchEnglish

From Latin 'fidelitas' (faithfulness, loyalty), which comes from 'fides' (faith, trust). The word entered English through Old French 'fidelité' in the 14th century, initially carrying the sense of loyalty to a person or duty. The meaning related to accuracy of reproduction developed in the late 19th and early 20th centuries, as audio and visual recording technologies began to describe how faithfully a device could reproduce an original signal.