Etymology
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insincere (adj.)
1620s (implied in insincerely), from Latin insincerus "spoiled, corrupted; not genuine, not pure, adulterated," from in- "not" (see in- (1)) + sincerus "genuine, candid" (see sincere). Related: Insincerely.
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insincerity (n.)
1540s, from in- (1) "not, opposite of" + sincerity, or else from Latin insincerus "not genuine, not pure; spoiled, corrupted" (see insincere).
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disingenuous (adj.)

"lacking in candor, insincere; not open, frank, or candid," 1650s, from dis- "opposite of" + ingenuous. Related: Disingenuously; disingenuousness; disenginuity (1640s).

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pseudo (n.)

late 14c., "false or spurious thing," especially "person falsely claiming divine authority," from Medieval Latin; see pseudo-. In modern use, of things, "imitated and exaggerated;" of persons, "pretentious, insincere," from 1945; as a noun in the modern sense from 1959. Related: Pseudish.

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bullshit (n.)

also bull shit, "eloquent and insincere rhetoric," 1914, American English slang; see bull (n.1) + shit (n.), probably because it smells. But bull in the sense of "trivial or false statements" (1914), which usually is associated with this, might be a continuation of Middle English bull "false talk, fraud" (see bull (n.3)).

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hollow (adj.)

c. 1200, adjective developed from Old English holh (n.) "hollow place, hole," from Proto-Germanic *hul-, from PIE root *kel- (1) "to cover, conceal, save." The figurative sense of "insincere" is attested from 1520s. Related: Hollowly. Spelling development followed that of fallow, sallow. Adverbial use in carry it hollow "take it completely" is first recorded 1660s, of unknown origin or connection. Hollow-eyed "having deep, sunken eyes" is attested from 1520s.

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adulation (n.)

"servile or insincere praise," late 14c., from Old French adulacion, from Latin adulationem (nominative adulatio) "a fawning; flattery, cringing courtesy," noun of action from past-participle stem of adulari "to flatter, fawn upon."

This is usually said to be from ad "to" (see ad-) + a stem meaning "tail," from a PIE *ul- "the tail" (source also of Sanskrit valah "tail-hair," and Lithuanian valai "horse's tail"). The original notion would be "to wag the tail" like a fawning dog (compare Greek sainein "to wag the tail," also "to flatter;" also see wheedle).

But de Vaan finds phonetic problems with these and concludes the etymology is uncertain, though he proposes a connection with avidus "eager," via *adulo- "who is eager toward something," hence "a flatterer." Adulation may proceed from true blind worship or be insincere, from hope of advantage.

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faithless (adj.)

c. 1300, "unbelieving," from faith + -less. Meaning "insincere, deceptive" is mid-14c. Related: Faithlessly; faithlessness.

Unfaithful ... especially means a lack of fidelity to trust or duty, a failure to perform what is due, however much may be implied in that. Faithless is negative in form, but positive in sense; the faithless man does something which is a breach of faith; the sleeping sentinel is unfaithful; the deserter is faithless. [Century Dictionary, 1895]
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lip-service (n.)
"something proffered but not performed, service with the lips only; insincere profession of good will," 1640s, from lip (n.) + service (n.1). Earlier in same sense was lip-labour (1530s). This was a general pattern in 16c.-17c., for example lip-wisdom (1580s), the wisdom of those who do not practice what they preach; lip-religion (1590s), lip-devotion "prayer without genuine faith or desire" (c. 1600); lip-comfort (1630s).
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artificial (adj.)

late 14c., "not natural or spontaneous," from Old French artificial, from Latin artificialis "of or belonging to art," from artificium "a work of art; skill; theory, system," from artifex (genitive artificis) "craftsman, artist, master of an art" (music, acting, sculpting, etc.), from stem of ars "art" (see art (n.)) + -fex "maker," from facere "to do, make" (from PIE root *dhe- "to set, put").

Earliest use in English is in the phrase artificial day "part of the day from sunrise to sunset" (as opposed to the natural day of 24 hours). Meaning "made by man, contrived by human skill and labor" is from early 15c. The word was applied from 16c. to anything made in imitation of, or as a substitute for, what is natural, whether real (light, tears) or not (teeth, flowers). Meaning "fictitious, assumed, not genuine" is from 1640s; that of "full of affectation, insincere" is from 1590s. Artificial insemination dates from 1894. Artificial intelligence "the science and engineering of making intelligent machines" was coined in 1956.

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