faithful

comparative more faithful · superlative most faithful · alternative archaic faithfull

1. Loyal; adhering firmly to person or cause.

   My dog is very faithful: he doesn't like to be petted by anybody else.

   1 more example

   Engels observes in one of his early writings that the Hegelian Left was the natural approach to communism, and that Hegelian communists such as Hess, Ruge, and Herwegh were a proof that the Germans must adopt communism if they were to remain faithful to their philosophical tradition from Kant to Hegel.

   1978 [1976], Leszek Kołakowski, translated by P[aul] S[teven] Falla, Main Currents of Marxism, volume I: The Founders, Oxford: Clarendon Press, translation of Główne nurty marksizmu: powstanie (in Polish), →ISBN, →OCLC, page 83

2. Having faith.

   The application of the old discipline, say the conservatives, would probably produce a smaller but more faithful Church.

   2009, Paul Lakeland, Church: Living Communion, page 162

3. Reliable; worthy of trust.

   My servant is very faithful.

4. Consistent with reality.

   I would consider that a very faithful reproduction.

5. Engaging in sexual relations only with one's spouse or long-term sexual partner.

   They had been faithful to each other all of their married life.

   1 more example

   She wanted to be free to explore casual affairs, but her man had to be faithful.

   1976, The Missouri Breaks

6. mathematicsInjective in specific contexts, e.g. of representations in representation or functors in category theory.
7. ring theoryOf a module, whose annihilator is zero.

plural faithfuls · alternative archaic faithfull

1. nounpluralThe practicing members of a religion or followers of a cause.

   The faithful pray five times a day.

   3 more examples

   The annual meeting was attended by the long-term party faithful.

   We Fremen have a saying: God created Arrakis to train the faithful. One cannot go against the word of God.

   1984, 2:11:25 from the start, in Dune (Science Fiction), spoken by Paul Atreides, →OCLC

   In attacking a vital broadcaster, the US president is once again holding others to standards he flouts. But the Maga faithful might not let his links to the disgraced financier go[.]

   2025 November 14, Jonathan Freedland, “Trump can get away with saying what he likes about the BBC. But Epstein? That’s his one vulnerability”, in The Guardian, →ISSN

2. Someone or something that is faithful or reliable.

   Earlier this year, as the recession put a damper on ticket sales, Maxwell said the easy route would have been to go for the tried-and-true old faithfuls.

   2009 September 30, Bruce DeMara, “Shaw's comedy gets teeth”, in Toronto Star