n. (pl. parentheses) 1 a a word, clause, or sentence inserted as an explanation or afterthought into a passage which is grammatically complete without it, and usu. marked off by brackets or dashes or commas. b (in pl.) a pair of round brackets () used for this. 2 an interlude or interval. in parenthesis as a parenthesis or afterthought.
[ LL f. Gk parenthesis f. parentithemi put in beside ]