discourtesy n.

word-forming element of Latin origin meaning 1. "lack of, not" (as in dishonest); 2. "opposite of, do the opposite of" (as in disallow); 3. "apart, away" (as in discard), from Old French des- or directly from Latin dis- "apart, asunder, in a different direction, between," figuratively "not, un-," also "exceedingly, utterly." Assimilated as dif- before -f- and to di- before most voiced consonants.

The Latin prefix is from PIE *dis- "apart, asunder" (source also of Old English te-, Old Saxon ti-, Old High German ze-, German zer-). The PIE root is a secondary form of *dwis- and thus is related to Latin bis "twice" (originally *dvis) and to duo, on notion of "two ways, in twain" (hence "apart, asunder").

In classical Latin, dis- paralleled de- and had much the same meaning, but in Late Latin dis- came to be the favored form and this passed into Old French as des-, the form used for compound words formed in Old French, where it increasingly had a privative sense ("not"). In English, many of these words eventually were altered back to dis-, while in French many have been altered back to de-. The usual confusion prevails.

As a living prefix in English, it reverses or negatives what it is affixed to. Sometimes, as in Italian, it is reduced to s- (as in spend, splay, sport, sdain for disdain, and the surnames Spencer and Spence).

c. 1200, curteisie, "courtly ideals; chivalry, chivalrous conduct; elegance of manners, politeness," also "a courteous act, act of civility or respect," from Old French curteisie, cortoisie "courtliness, noble sentiments; courteousness; generosity" (Modern French courtoisie), from curteis "courteous" (see courteous).

From c. 1300 as "good will, kindness," also "a reward, a gift;" mid-14c. as "refinement, gentlemanly conduct." A specialized sense of curteisie is the source of English curtsy. A courtesy title (1829) is one to which one has no valid claim but which is assumed or given by popular consent. Courtesy call "visit made for the sake of politeness" is by 1898.