1640s, "empty" (implied in vacuousness), from Latin vacuus "empty, void, free" (from PIE *wak-, extended form of root *eue- "to leave, abandon, give out"). Figurative sense of "empty of ideas, without intelligent expression" is from 1848. Related: Vacuously.

1540s, "emptiness of space," from Latin vacuum "an empty space, vacant place, a void," noun use of neuter of vacuus "empty, unoccupied, devoid of," figuratively "free, unoccupied," from Proto-Italic *wakowos, related to the source of Latin  vacare "to be empty" (from PIE *wak-, extended form of root *eue- "to leave, abandon, give out"), with adjectival suffix -uus. Properly a loan-translation of Greek kenon, literally "that which is empty."

Meaning "a space emptied of air" is attested from 1650s. Vacuum tube "glass thermionic device" is attested from 1859. Vacuum cleaner is from 1903; shortened form vacuum (n.) first recorded 1910.

The metaphysicians of Elea, Parmenides and Melissus, started the notion that a vacuum was impossible, and this became a favorite doctrine with Aristotle. All the scholastics upheld the maxim that "nature abhors a vacuum." [Century Dictionary]

c. 1300, "devoid of real value, idle, unprofitable," from Old French vain, vein "worthless, void, invalid, feeble; conceited" (12c.), from Latin vanus "empty, void," figuratively "idle, fruitless," from PIE *wano-, suffixed form of root *eue- "to leave, abandon, give out."

Meaning "conceited, elated with a high opinion of oneself" first recorded 1690s in English; earlier "silly, idle, foolish" (late 14c.). Phrase in vain "to no effect" (c. 1300, after Latin in vanum) preserves the original sense. Related: Vainly; vainness. Compare also vainglory.

"disappear quickly," c. 1300, from shortened form of esvaniss-, stem of Old French esvanir "disappear; cause to disappear," from Vulgar Latin *exvanire, from Latin evanescere "disappear, pass away, die out," from ex "out" (see ex-) + vanescere "vanish," inchoative verb from vanus "empty, void," from PIE *wano-, suffixed form of root *eue- "to leave, abandon, give out." Related: Vanished; vanishing; vanishingly. Vanishing point in perspective drawing is recorded from 1797.

c. 1200, "that which is vain, futile, or worthless," from Old French vanite "self-conceit; futility; lack of resolve" (12c.), from Latin vanitatem (nominative vanitas) "emptiness, aimlessness; falsity," figuratively "vainglory, foolish pride," from vanus "empty, void," figuratively "idle, fruitless," from PIE *wano-, suffixed form of root *eue- "to leave, abandon, give out." Meaning "self-conceited" in English is attested from mid-14c. Vanity table is attested from 1936. Vanity Fair is from "Pilgrim's Progress" (1678).

early 15c., "speak vainly or proudly," from Anglo-French vaunter, Old French vanter "to praise, speak highly of," from Medieval Latin vanitare "to boast," frequentative of Latin vanare "to utter empty words," from vanus "empty, void," figuratively "idle, fruitless," from PIE *wano-, suffixed form of root *eue- "to leave, abandon, give out." Also short for avaunten "to boast" (see vaunt (n.)). Related: Vaunted; vaunting.

c. 1300, "unoccupied, vacant," from Anglo-French and Old French voide, viude "empty, vast, wide, hollow, waste, uncultivated, fallow," as a noun, "opening, hole; loss," from Latin vocivos "unoccupied, vacant," related to vacare "be empty," from PIE *wak-, extended form of root *eue- "to leave, abandon, give out." Meaning "lacking or wanting" (something) is recorded from early 15c. Meaning "legally invalid, without legal efficacy" is attested from mid-15c.

Old English wanian "make or become smaller gradually, diminish, decline, fade," from Proto-Germanic *wanōnan (source also of Old Saxon wanon, Old Norse vana, Old Frisian wania, Middle Dutch waenen, Old High German wanon "to wane, to grow less"), from *wano- "lacking," from PIE *weno-, suffixed form of root *eue- "to leave, abandon, give out." Related: Waned; waning; wanes.

c. 1200, "to be lacking," from Old Norse vanta "to lack, want," earlier *wanaton, from Proto-Germanic *wanen, from PIE *weno-, suffixed form of root *eue- "to leave, abandon, give out." The meaning "desire, wish for, feel the need of" is recorded by 1706.

early 14c., wan-towen, "resistant to control; willful," from Middle English privative word-forming element wan- "wanting, lacking, deficient," from Old English wan-, which was used interchangeably with un- (1), and is cognate with Dutch wan- (as in wanbestuur "misgovernment," wanluid "discordant sound"), Swedish and Danish van-, from Proto-Germanic *wano- "lacking," from PIE *weno-, suffixed form of root *eue- "to leave, abandon, give out." Common in Old and Middle English, still present in 18c. glossaries of Scottish and Northern English; this word is its sole modern survival.

Second element is Middle English towen, from Old English togen, past participle of teon "to train, discipline;" literally "to pull, draw," from Proto-Germanic *teuhan (source also of Old High German ziohan "to pull," from Proto-Germanic *teuhan; see tug (v.)). The basic notion perhaps is "ill-bred, poorly brought up;" compare German ungezogen "ill-bred, rude, naughty," literally "unpulled." Especially of sexual indulgence from late 14c. Meaning "inhumane, merciless" is from 1510s. Related: Wantonly; wantonness.

As Flies to wanton Boyes are we to th' Gods, They kill vs for their sport. [Shakespeare, "Lear," 1605]