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faithful

adj. · n.
US //ˈfeɪθfəɫ// UK //fˈeɪθfəl// faith·ful
  1. 1 loyal (adj.)
    B2 Upper Intermediate

    staying loyal to a person, a group, or a set of beliefs over a long time.

    adhering firmly and devotedly to a person, cause, or idea.

    Example

    He remained a faithful friend even during the most difficult years of her life.

    Example

    Despite the political upheaval, the general remained faithful to the constitution, refusing to support the attempted coup.
  2. 2 monogamous (adj.)
    B2 Upper Intermediate

    having a sexual relationship with only one person, such as a husband or wife.

    remaining sexually loyal to a single spouse or long-term partner.

    Example

    They promised to be faithful to each other when they got married.

    Example

    The study examined the social factors that encourage couples to remain faithful throughout decades of marriage.
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  1. 3 accurate (adj.)
    C1 Advanced Formal

    exactly like the original thing or the truth.

    representing something with a high degree of accuracy or truth; consistent with reality.

    Example

    The film is a faithful version of the famous book.

    Example

    The architect insisted on a faithful restoration of the cathedral, using only materials that were available in the twelfth century.
  2. 4 mathematics (adj.)
    C2 Proficiency Technical Math

    a technical way to describe certain types of mathematical relationships.

    describing a representation or functor that is injective, or a module whose annihilator is zero.

    Example

    The professor explained why this specific representation is considered faithful.

    Example

    In category theory, a faithful functor is one that is injective on morphisms for every pair of objects in the source category.
    • injective
  3. 5 the believers (n.)
    C1 Advanced Formal Religion

    the people who follow a religion or a specific cause.

    the collective body of practicing members of a religion or devoted followers of a movement.

    Example

    The priest spoke to the faithful during the morning service.

    Example

    The party leader gathered the faithful for a final rally on the eve of the national election.

    Usage

    Usually used as 'the faithful' to refer to a group of people.
Origin

From Middle English feithful, equivalent to faith + -ful.

Word family

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