English Reference
noun

fidelity

n.
US /ˌfaɪˈdɛɫəti/ UK /fɪdˈɛlɪti/ fi·deli·ty UK spelling fidelities

  1. 01 B2 Upper Intermediate

    being loyal and faithful to a husband, wife, or partner.

    faithfulness to a spouse or romantic partner, specifically regarding sexual or emotional exclusivity.

    Simple

    They promised lifelong fidelity to each other during their wedding ceremony.

    In context

    The novel explores the complexities of marital fidelity in an era where social expectations were rapidly shifting.

    infidelityunfaithfulnessbetrayal
  2. 02 C1 Advanced Formal

    the quality of being loyal to your duties, a country, or a set of beliefs.

    strict adherence to one's promises, duties, or allegiances.

    Simple

    The officer was awarded a medal for his long fidelity to the crown.

    In context

    His unwavering fidelity to the principles of the revolution made him a respected, if somewhat rigid, leader.

    disloyaltytreachery
  3. 03 B2 Upper Intermediate Technical Science

    how accurately a sound or image is copied or played back.

    the degree of exactness with which something is copied or reproduced, particularly in audio or visual technology.

    Simple

    The new speakers offer incredible fidelity, making it feel like the band is in the room.

    In context

    The digital restoration of the film achieved a level of fidelity that revealed details previously lost in the grainy original print.

    Usage

    Often used in the phrase 'high fidelity' or 'hi-fi'.

  4. 04 C2 Proficiency ArchaicFormal Religion

    staying true to your religious beliefs or to God.

    faithfulness to a deity or a specific religious doctrine.

    Simple

    The monks lived a life of quiet fidelity to their ancient traditions.

    In context

    The historical text emphasizes the martyr's fidelity to his faith even in the face of extreme persecution.

    pietydevoutness

Probably not, as he tended to insist on fidelity to his vision, right down to the set-dressing.

The Guardian· 1 Sept 2026
This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated