faith (n.)youdaoicibaDictYouDict[faith 词源字典]
mid-13c., faith, feith, fei, fai "faithfulness to a trust or promise; loyalty to a person; honesty, truthfulness," from Anglo-French and Old French feid, foi "faith, belief, trust, confidence; pledge" (11c.), from Latin fides "trust, faith, confidence, reliance, credence, belief," from root of fidere "to trust," from PIE root *bheidh- "to trust" (source also of Greek pistis "faith, confidence, honesty;" see bid). For sense evolution, see belief. Accomodated to other English abstract nouns in -th (truth, health, etc.).

From early 14c. as "assent of the mind to the truth of a statement for which there is incomplete evidence," especially "belief in religious matters" (matched with hope and charity). Since mid-14c. in reference to the Christian church or religion; from late 14c. in reference to any religious persuasion.
And faith is neither the submission of the reason, nor is it the acceptance, simply and absolutely upon testimony, of what reason cannot reach. Faith is: the being able to cleave to a power of goodness appealing to our higher and real self, not to our lower and apparent self. [Matthew Arnold, "Literature & Dogma," 1873]
From late 14c. as "confidence in a person or thing with reference to truthfulness or reliability," also "fidelity of one spouse to another." Also in Middle English "a sworn oath," hence its frequent use in Middle English oaths and asseverations (par ma fay, mid-13c.; bi my fay, c. 1300).[faith etymology, faith origin, 英语词源]
faithful (adj.)youdaoicibaDictYouDict
early 14c., "sincerely religious, devout, pious," especially in reference to Christian practice; mid-14c., "loyal (to a lord, friend, spouse, etc.); true; honest, trustworthy," from faith + -ful. From late 14c. in reference to a tale, a report, etc., "accurate, reliable, true to the facts." The noun sense of "true believer, one who is full of faith" is from late 14c. (Church Latin used fideles in same sense). Related: Faithfully; faithfulness. Old Faithful geyser named 1870 by explorer Gen. Henry Dana Washburn (1832-1871), surveyor-general of the Montana Territory, in reference to the regularity of its outbursts.
fealty (n.)youdaoicibaDictYouDict
c. 1300, feaute, from Old French feauté, earlier fealte, "loyalty, fidelity; homage sworn by a vassal to his overlord; faithfulness," from Latin fidelitatem (nominative fidelitas) "faithfulness, fidelity," from fidelis "loyal, faithful" (see fidelity).
fidelity (n.)youdaoicibaDictYouDict
early 15c., "faithfulness, devotion," from Middle French fidélité (15c.), from Latin fidelitatem (nominative fidelitas) "faithfulness, adherence, trustiness," from fidelis "faithful, true, trusty, sincere," from fides "faith" (see faith). From 1530s as "faithful adherence to truth or reality;" specifically of sound reproduction from 1878.
infidelity (n.)youdaoicibaDictYouDict
c. 1400, "want of faith, unbelief in religion; false belief, paganism;" also (early 15c.) "unfaithfulness or disloyalty to a person" (originally to a sovereign, by 16c. to a lover or spouse), from French infidélité, from Latin infidelitatem (nominative infidelitas) "unfaithfulness, faithlessness," noun of quality from infidelis (see infidel).
jealous (adj.)youdaoicibaDictYouDict
c. 1200, gelus, later jelus (early 14c.), "possessive and suspicious," originally in the context of sexuality or romance; in general use late 14c.; also in a more positive sense, "fond, amorous, ardent," from c. 1300, from Old French jalos "keen, zealous; avaricious; jealous" (12c., Modern French jaloux), from Late Latin zelosus, from zelus "zeal," from Greek zelos, sometimes "jealousy," but more often in a good sense ("emulation, rivalry, zeal"). See zeal. In biblical language (early 13c.) "tolerating no unfaithfulness."
Most of the words for 'envy' ... had from the outset a hostile force, based on 'look at' (with malice), 'not love,' etc. Conversely, most of those which became distinctive terms for 'jealousy' were originally used also in a good sense, 'zeal, emulation.' [Buck, pp.1138-9]
Among the ways to express this in other tongues are Swedish svartsjuka, literally "black-sick," from phrase bara svarta strumpor "wear black stockings," also "be jealous." Danish skinsyg "jealous," literally "skin-sick," is from skind "hide, skin" said to be explained by Swedish dialectal expression fa skinn "receive a refusal in courtship."
piety (n.)youdaoicibaDictYouDict
early 14c. (late 12c. as a surname), "mercy, tenderness, pity," from Old French piete "piety, faith; pity, compassion" (12c.), from Latin pietatem (nominative pietas) "dutiful conduct, sense of duty; religiousness, piety; loyalty, patriotism; faithfulness to natural ties," in Late Latin "gentleness, kindness, pity;" from pius "kind" (see pious). Meaning "piousness" attested in English from c. 1600. Also see pity (n.).
troth (n.)youdaoicibaDictYouDict
"truth, verity," late 12c., from a phonetic variant of Old English treowð "faithfulness, veracity, truth" (see truth). Restricted to Midlands and Northern England dialect after 16c., and to certain archaic phrases (such as plight one's troth). Also see betroth.
truce (n.)youdaoicibaDictYouDict
"mutually agreed-upon temporary intermission of hostilities," early 13c., triws, variant of trewes, originally plural of trewe "faith, assurance of faith, covenant, treaty," from Old English treow "faith, truth, fidelity; pledge, promise, agreement, treaty," from Proto-Germanic *treuwaz- (cognates: Old Frisian triuwe, Middle Dutch trouwe, Dutch trouw, Old High German triuwa, German treue, Gothic triggwa "faith, faithfulness"). Related to Old English treowe "faithful" (see true (adj.)). The Germanic word was borrowed into Late Latin as tregua, hence French trève, Italian tregua.
trust (n.)youdaoicibaDictYouDict
c. 1200, "reliance on the veracity, integrity, or other virtues of someone or something; religious faith," from Old Norse traust "help, confidence, protection, support," from Proto-Germanic abstract noun *traustam (cognates: Old Frisian trast, Dutch troost "comfort, consolation," Old High German trost "trust, fidelity," German Trost "comfort, consolation," Gothic trausti "agreement, alliance"), from Proto-Germanic *treuwaz-, source of Old English treowian "to believe, trust," and treowe "faithful, trusty" (see true (adj.)).

from c. 1300 as "reliability, trustworthiness; trustiness, fidelity, faithfulness;" from late 14c. as "confident expectation" and "that on which one relies." From early 15c. in legal sense of "confidence placed in a one who holds or enjoys the use of property entrusted to him by its legal owner;" mid-15c. as "condition of being legally entrusted." Meaning "businesses organized to reduce competition" is recorded from 1877. Trust-buster is recorded from 1903.
truth (n.)youdaoicibaDictYouDict
Old English triewð (West Saxon), treowð (Mercian) "faith, faithfulness, fidelity, loyalty; veracity, quality of being true; pledge, covenant," from triewe, treowe "faithful" (see true (adj.)), with Proto-Germanic abstract noun suffix *-itho (see -th (2)).

Sense of "something that is true" is first recorded mid-14c. Meaning "accuracy, correctness" is from 1560s. English and most other IE languages do not have a primary verb for for "speak the truth," as a contrast to lie (v.). Truth squad in U.S. political sense first attested in the 1952 U.S. presidential election campaign.
At midweek the Republican campaign was bolstered by an innovation--the "truth squad" ..., a team of senators who trailed whistle-stopping Harry Truman to field what they denounced as his wild pitches. ["Life," Oct. 13, 1952]



Let [Truth] and Falsehood grapple; who ever knew Truth put to the worse, in a free and open encounter. [Milton, "Areopagitica," 1644]
unfaithful (adj.)youdaoicibaDictYouDict
mid-14c., "acting falsely," from un- (1) "not" + faithful. In Middle English it also had a sense of "infidel, unbelieving, irreligious" (late 14c.). Sense of "not faithful in marriage" is attested from 1828. Related: Unfaithfully; unfaithfulness.
untruth (n.)youdaoicibaDictYouDict
Old English untreowþ "unfaithfulness, treachery," from un- (1) "not" + truth (n.). Similar formation in Old Norse utrygð. Meaning "falsehood" is attested from mid-15c., as is that of "a lie." Related: Untruthful.
Varangian (n.)youdaoicibaDictYouDict
one of the Northmen who ravaged the Baltic coast in 9c. and by tradition overran part of western Russia and founded a dynasty there," 1788, from Medieval Latin Varangus, from Byzantine Greek Barangos, a name ultimately (via Slavic) from Old Norse væringi "a Scandinavian," properly "a confederate," from var- "pledge, faith," related to Old English wær "agreement, treaty, promise," Old High German wara "faithfulness" (see very). Attested in Old Russian as variagi; surviving in Russian varyag "a pedlar," Ukrainian varjah "a big strong man."
Vulcan (n.)youdaoicibaDictYouDict
god of fire and metal-work in Roman mythology, 1510s, from Latin Vulcanus, Volcanus, according to Klein a word of Etruscan origin. Often with allusions to his lameness and the unfaithfulness of his wife, Venus. As the name of a hypothetical planet between Mercury and the Sun, it is attested from 1860. French physician Edmond Modeste Lescarbault claimed to have discovered it crossing the Sun's disk in 1859. The Roman feast of Vulcanalia was on Aug. 23.