parenthesis

1. A clause, phrase, or word which is inserted into a grammatically complete passage of text for explanation or as an aside, and usually marked off with brackets, commas, or dashes. (countable)
2. An aside serving as an explanation; also, an afterthought. (countable)
3. The making of asides or explanations in grammatically complete passages of text. (uncountable)
4. Either of a pair of brackets, chiefly the round brackets "(" and ")" but occasionally also the square brackets "[" and "]", which are used together to enclose parenthetical material in a text. (countable)
5. Either of a pair of curved lines or shapes resembling a round bracket. (countable, uncountable)
6. Either of a pair of brackets used to clarify an expression by grouping terms affected by a common operator, or to enclose the components of a vector or the elements of a matrix. (countable, uncountable)
7. An intervening event; an interlude, an interruption. (countable, figuratively)

Plural parentheses