c. 1300, "deceitfulness, treachery, dishonesty," from Old French fauseté "falsehood" (12c., Modern French fausseté), from Late Latin falsitatem (nominative falsitas), from Latin falsus "erroneous, mistaken" (see false). From late 14c. as "untrue statement or doctrine;" from 1570s as "character of being not true."

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).