parenthesis

noun4

1. •
   A clause, phrase or word which is inserted (usually for explanation or amplification) into a passage which is already grammatically complete, and usually marked off with brackets, commas or dashes.

   • How expressive this little parenthesis: "Sakuntalâ makes a chiding gesture with her finger"! — 1903
2. •
   Either of a pair of brackets, especially (mainly US) round brackets, ( and ) (used to enclose parenthetical material in a text).
3. •
   Such brackets as used to clarify expressions by grouping those terms affected by a common operator, or to enclose the components of a vector or the elements of a matrix.
4. •
   (rhetoric) A digression; the use of such digressions.