Etymology
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falter (v.)
late 14c., "to stagger, totter," of unknown origin, possibly from a Scandinavian source (compare Old Norse faltrask "be burdened, hesitate, be troubled"), or else a frequentative of Middle English falden "to fold," influenced by fault (but OED rejects any direct connection to that word). Of the tongue, "to stammer," mid-15c. Related: Faltered; faltering.
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unfaltering (adj.)
1660s, from un- (1) "not" + present participle of falter (v.). Related: Unfalteringly.
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papillon (n.)

1907 as a breed of dog, from French papillon, literally "butterfly," from Latin papilionem (nominative papilio) "butterfly," which is perhaps from a reduplicated form of a PIE root *pl- "to fly, flutter." The Latin word is believed to be cognate with Old English fifealde, Old Saxon fifoldara, Old Norse fifrildi, Old High German vivaltra, German Falter "butterfly;" Old Prussian penpalo, Lithuanian piepala, Russian perepel "quail." The dog was so called for the shape of the ears. Middle English had papilloun "a butterfly," from Old French.

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feint (v.)
c. 1300, feinten, "to deceive, pretend" (obsolete), also "become feeble or exhausted; to lack spirit or courage," from Middle English feint (adj.) "feigned, false, counterfeit" and directly from Old French feint "false, deceitful; weak, lazy," past participle of feindre "to hesitate, falter; lack courage; feign, pretend, simulate," from Latin fingere "to touch, handle; devise; fabricate, alter, change" (from PIE root *dheigh- "to form, build"). Sense of "make a sham attack, make a pretended blow" is attested by 1833, from the noun (1680s as "a feigned attack"). Related: Feinted; feinting.
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feign (v.)
A 17c. respelling of fain, fein, from Middle English feinen, feynen "disguise or conceal (deceit, falsehood, one's real meaning); dissemble, make false pretenses, lie; pretend to be" (c. 1300), from Old French feindre "hesitate, falter; be indolent; lack courage; show weakness," also transitive, "to shape, fashion; depict, represent; feign, pretend; imitate" (12c.), from Latin fingere "to touch, handle; devise; fabricate, alter, change" (from PIE root *dheigh- "to form, build").

From late 14c. as "simulate (an action, an emotion, etc.)." Related: Feigned; feigning. The older spelling is that of faint, feint, but this word acquired a -g- in imitation of the French present participle stem feign- and the Latin verb.
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faint (adj.)
c. 1300, "enfeebled; wearied, exhausted," from Old French faint, feint "false, deceitful; sham, artificial; weak, faint, lazy, indolent, cowardly," past participle of feindre "hesitate, falter, be indolent, show weakness, avoid one's duty by pretending," from Latin fingere "to touch, handle; devise; fabricate, alter, change" (from PIE root *dheigh- "to form, build"). Also from c. 1300 as "deceitful; unreliable; false." Meaning "wanting in spirit or courage, cowardly" (a sense now mostly encountered in faint-hearted) is from early 14c. From early 15c. of actions, functions, colors, etc., "weak, feeble, poor." Meaning "producing a feeble impression upon the senses" is from 1650s.
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