It forms all or part of: avoid; devastation; devoid; evacuate; evanescent; vacant; vacate; vacation; vacuity; vacuole; vacuous; vacuum; vain; vanish; vanity; vaunt; void; wane; want; wanton; waste.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit una- "deficient;" Avestan va- "lack," Persian vang "empty, poor;" Armenian unain "empty;" Latin vacare "to be empty," vastus "empty, waste," vanus "empty, void," figuratively "idle, fruitless;" Old English wanian "to lessen," wan "deficient;" Old Norse vanta "to lack."
"scheming, licentious, sexually voracious woman," by 1795, in reference to Valeria Messalina (died 48 C.E.), notorious third wife of the Roman emperor Claudius, long a figure of vanity and immorality.
"effort to attract love from a motive of vanity or amusement, trifling in love," 1650s, from French coquetterie, from coqueter (v.) "to flirt," originally "to swagger or strut like a cock," from coquet (see coquet).
Coquetry whets the appetite; flirtation depraves it .... ["Ik. Marvel" (Donald Grant Mitchell), "Reveries of a Bachelor," 1851]
late 15c., "blown over, passed away" (as a wind or storm), past-participle adjective from verb overblow "to blow over the top of," of a storm, "to abate, pass on" (late 14c.), from over- + blow (v.1). Sense of "past the time of blossoming or blooming" (as a flower), 1610s, is from blow (v.2). Figurative meaning "inflated, puffed up" (with vanity, etc.) is from 1864.