from
The Collaborative International Dictionary of English v.0.48
Parenthesis \Pa*ren"the*sis\ (p[.a]*r[e^]n"th[-e]*s[i^]s), n.;
pl. {Parentheses}. [NL., fr. Gr. pare`nqesis, fr.
parentiqe`nai to put in beside, insert; para` beside + 'en in
+ tiqe`nai to put, place. See {Para-}, {En-}, 2, and
{Thesis}.]
[1913 Webster]
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. "Seldom mentioned without a derogatory
parenthesis." --Sir T. Browne.
[1913 Webster]
Don't suffer every occasional thought to carry you
away into a long parenthesis. --Watts.
[1913 Webster]
2. (Print.) One of the curved lines () which inclose a
parenthetic word or phrase.
[1913 Webster]
Note: Parenthesis, in technical grammar, is that part of a
sentence which is inclosed within the recognized sign;
but many phrases and sentences which are punctuated by
commas are logically parenthetical. In def. 1, the
phrase "by way of comment or explanation" is inserted
for explanation, and the sentence would be
grammatically complete without it. The present tendency
is to avoid using the distinctive marks, except when
confusion would arise from a less conspicuous
separation.
[1913 Webster]