[pa.ren.the.sis] n, pl -the.ses [LL, fr. Gk, lit., act of inserting, fr. parentithenai to insert, fr. para- + en- en- + tithenai to place--more at do] (ca. 1550) 1 a: an amplifying or explanatory word, phrase, or sentence inserted in a passage from which it is usu. set off by punctuation b: a remark or passage that departs from the theme of a discourse: digression
2: interlude, interval
3: one or both of the curved marks ( ) used in writing and printing to enclose a parenthetical expression or to group a symbolic unit in a logical or mathematical expression -- par.en.thet.i.cal also par.en.thet.ic adj -- par.en.thet.i.cal.ly adv