Parenthesis

n.	1.	A word, phrase, or sentence, by way of comment or explanation, inserted in, or attached to, a sentence which would be grammatically complete without it. It is usually inclosed within curved lines (see def. 2 below), or dashes. Don't suffer every occasional thought to carry you away into a long parenthesis. - Watts.
	2.	(Print.) One of the curved lines () which inclose a parenthetic word or phrase.

Noun	1.	parenthesis - either of two punctuation marks (or) used to enclose textual material
	2.	parenthesis - a message that departs from the main subject Synonyms: digression, divagation, excursus, aside

anastrophe, aside, broken thread, brokenness, chiasmus, disconnectedness, disconnection, discontinuance, discontinuation, discontinuity, discontinuousness, discreteness, disjunction, episode, fitfulness, hypallage, hyperbaton, hysteron proteron, incoherence, incompleteness, infix, injection, insert, insertion, insinuation, intercalation, interjection, interlineation, interlocution, intermittence, interpolation, introduction, irregularity, metastasis, metathesis, non sequitur, noncontinuance, nonlinearity, nonseriality, nonuniformity, obiter dictum, palindrome, remark, side remark, synchysis, tmesis, tossing-in