early 14c., bealte, "physical attractiveness," also "goodness, courtesy," from Anglo-French beute, Old French biauté "beauty, seductiveness, beautiful person" (12c., Modern French beauté), earlier beltet, from Vulgar Latin bellitatem (nominative bellitas) "state of being pleasing to the senses" (source also of Spanish beldad, Italian belta), from Latin bellus "pretty, handsome, charming," in classical Latin used especially of women and children, or ironically or insultingly of men, perhaps from PIE *dw-en-elo-, diminutive of root *deu- (2) "to do, perform; show favor, revere." Famously defined by Stendhal as la promesse de bonheur "the promise of happiness."
[I]t takes the one hundred men in ten million who understand beauty, which isn't imitation or an improvement on the beautiful as already understood by the common herd, twenty or thirty years to convince the twenty thousand next most sensitive souls after their own that this new beauty is truly beautiful. [Stendhal, "Life of Henry Brulard"]
Replaced Old English wlite. Concrete meaning "a beautiful woman" in English is first recorded late 14c. Beauty-sleep "sleep before midnight" (popularly regarded as the most refreshing) is attested by 1850. Beauty-spot "dark spot placed on the face formerly by women to heighten beauty" is from 1650s. Beauty-contest is from 1885; beauty-queen is from 1922 (earlier it was a show-name of cattle and hogs). Beauté du diable (literally "devil's beauty") is used as a French phrase in English from 1825.
But as it is hardly possible to define all the properties which constitute beauty, we may observe in general, that beauty consists in whatever pleases the eye of the beholder, whether in the human body, in a tree, in a landscape or in any other object. [from definition of BEAUTY in Noah Webster's "Dictionary of the English Language," 1828]