Etymology
Advertisement
fay (n.)
"fairy," late 14c., from Old French fae (12c., Modern French fée), from Vulgar Latin *fata "goddess of fate," fem. singular of Latin fata (neuter plural), literally "the Fates" (see fate (n.)). Adjective meaning "homosexual" is attested from 1950s.
Related entries & more 
Advertisement
Fay 
fem. proper name, in some cases from Middle English fei, Old French fei "faith," or else from fay "fairy."
Related entries & more 
fairy (n.)

c. 1300, fairie, "the country or home of supernatural or legendary creatures; fairyland," also "something incredible or fictitious," from Old French faerie "land of fairies, meeting of fairies; enchantment, magic, witchcraft, sorcery" (12c.), from fae "fay," from Latin fata "the Fates," plural of fatum "that which is ordained; destiny, fate," from PIE root *bha- (2) "to speak, tell, say." Also compare fate (n.), also fay.

In ordinary use an elf differs from a fairy only in generally seeming young, and being more often mischievous. [Century Dictionary]

But that was before Tolkien. As a type of supernatural being from late 14c. [contra Tolkien; for example "This maketh that ther been no fairyes" in "Wife of Bath's Tale"], perhaps via intermediate forms such as fairie knight "supernatural or legendary knight" (c. 1300), as in Spenser, where faeries are heroic and human-sized. As a name for the diminutive winged beings in children's stories from early 17c.

Yet I suspect that this flower-and-butterfly minuteness was also a product of "rationalization," which transformed the glamour of Elfland into mere finesse, and invisibility into a fragility that could hide in a cowslip or shrink behind a blade of grass. It seems to become fashionable soon after the great voyages had begun to make the world seem too narrow to hold both men and elves; when the magic land of Hy Breasail in the West had become the mere Brazils, the land of red-dye-wood. [J.R.R. Tolkien, "On Fairy-Stories," 1947]

Hence, figurative adjective use in reference to lightness, fineness, delicacy. Slang meaning "effeminate male homosexual" is recorded by 1895. Fairy ring, of certain fungi in grass fields (as we would explain it now), is from 1590s. Fairy godmother attested from 1820. Fossil Cretaceous sea urchins found on the English downlands were called fairy loaves, and a book from 1787 reports that "country people" in England called the stones of the old Roman roads fairy pavements.

Related entries & more 
*bha- (2)

*bhā-; Proto-Indo-European root meaning "to speak, tell, say."

It forms all or part of: abandon; affable; anthem; antiphon; aphasia; aphonia; aphonic; apophasis; apophatic; ban (n.1) "proclamation or edict;" ban (v.); banal; bandit; banish; banlieue; banns (n.); bifarious; blame; blaspheme; blasphemy; boon (n.); cacophony; confess; contraband; defame; dysphemism; euphemism; euphony; fable; fabulous; fado; fairy; fame; famous; fandango; fatal; fate; fateful; fatuous; fay; gramophone; heterophemy; homophone; ineffable; infamous; infamy; infant; infantile; infantry; mauvais; megaphone; microphone; monophonic; nefandous; nefarious; phatic; -phone; phone (n.2) "elementary sound of a spoken language;" phoneme; phonetic; phonic; phonics; phono-; pheme; -phemia; Polyphemus; polyphony; preface; profess; profession; professional; professor; prophecy; prophet; prophetic; quadraphonic; symphony; telephone; xylophone.

It is the hypothetical source of/evidence for its existence is provided by: Greek pheme "speech, voice, utterance, a speaking, talk," phōnē "voice, sound" of a human or animal, also "tone, voice, pronunciation, speech," phanai "to speak;" Sanskrit bhanati "speaks;" Latin fari "to say," fabula "narrative, account, tale, story," fama "talk, rumor, report; reputation, public opinion; renown, reputation;" Armenian ban, bay "word, term;" Old Church Slavonic bajati "to talk, tell;" Old English boian "to boast," ben "prayer, request;" Old Irish bann "law."

Related entries & more 
Fata Morgana (n.)
1818, literally "Fairy Morgana," mirage especially common in the Strait of Messina, Italy, from Morgana, the "Morgan le Fay" of Anglo-French poetry, sister of King Arthur, located in Calabria by Norman settlers. Morgan is Welsh, "sea-dweller." There is perhaps, too, here an influence of Arabic marjan, literally "pearl," also a fem. proper name, popularly the name of a sorceress.
Related entries & more 
Advertisement
ofay (n.)
African-American vernacular, "white person," 1925, of unknown origin. If, as is sometimes claimed, it derives from an African word, none corresponding to it has been found. Perhaps the most plausible speculation is Yoruba ófé "to disappear" (as from a powerful enemy), with the sense transferred from the word of self-protection to the source of the threat. OED regards the main alternative theory, that it is pig Latin for foe, to be no more than an "implausible guess." Sometimes shortened to fay (1927).
Related entries & more 
faith (n.)
Origin and meaning of faith

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, confide, persuade." For sense evolution, see belief. Accommodated 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).

Related entries & more 
porcupine (n.)

rodent noted for its stout, clumsy body and the defensive spines or quills that cover the body and tail, c. 1400, porke despyne, from Old French porc-espin (early 13c., Modern French porc-épic), literally "spine hog," from Latin porcus "hog" (from PIE root *porko- "young pig") + spina "thorn, spine" (see spine). The word had many forms in Middle English and early Modern English, including portepyn (influenced by port "to carry," as though "carry-spine"), porkpen, porkenpick, porpoynt, and Shakespeare's porpentine (in "Hamlet"). The same notion forms the name in other languages (Dutch stekel-varken, German Stachelschwein).

The spines grow mostly on the rump and back of the broad flat tail ; they are quite loosely attached, and when the animal slaps with its tail (its usual mode of defense) some quills may be flirted to a distance. Something like this, no doubt, gives rise to the popular notion that the porcupine "shoots" its quills at an enemy. [Century Dictionary] 
May (9 years old)—"Papa, things pertaining to a horse are equine, to cows bovine, to cats feline, to dogs canine, but to hogs, is what?"
Fay (5 years)—"Porcupine, O tourse."
[Health, August 1904]
Related entries & more