Merriam-Webster Collegiate Dictionary - faith

 I. noun  (plural ~s)  Etymology: Middle English feith, from Anglo-French feid, fei, from Latin fides; akin to Latin fidere to trust — more at bide  Date: 13th century  1.  a. allegiance to duty or a person ; loyalty  b.  (1) fidelity to one's promises  (2) sincerity of intentions  2.  a.  (1) belief and trust in and loyalty to God  (2) belief in the traditional doctrines of a religion  b.  (1) firm belief in something for which there is no proof  (2) complete trust  3. something that is believed especially with strong conviction; especially a system of religious beliefs the Protestant ~  Synonyms: see belief  II. transitive verb  Date: 15th century archaic believe, trust