Origin and history of *ko-

also etcetera, early 15c., from Latin et cetera, literally "and the others," from et "and" + neuter plural of ceterus "the other, other part, that which remains," from Proto-Italic *ke-etero‑, from *ke-, variant form of PIE root *ko-, the stem of demonstrative pronoun meaning "this" + *etero‑ "other (of two), again, a second time, again," a PIE adjective of comparison.

The common form of the abbreviation before 20c. was &c., but etc. now prevails.

1610s, "to lay waste, devastate" (obsolete); 1620s, "to vex by repeated attacks," from French harasser "tire out, vex" (16c.), which is of uncertain origin; possibly from Old French harer "stir up, provoke; set a dog on" (according to Watkins, from Frankish *hara "over here, hither," from Proto-Germanic *hi‑, from PIE *ki-, variant form of root *ko-, the stem of demonstrative pronoun meaning "this"), and perhaps blended with Old French harier "to harry, draw, drag" [Barnhart]. Related: Harassed; harassing.

Harass, as applied to mind or body, suggests the infliction of the weariness that comes from the continuance or repetition of trying experiences, so that there is not time for rest. Torment implies the infliction of acute pain, physical or mental, and is frequently used in the sense of harassing by frequent return. [Century Dictionary, 1897]