Date: circa 1942 any of various conventional devices (as braces, brackets, parentheses, or vinculums) used in mathematics to indicate that two or more terms are to be treated as one quantity
SIGN OF AGGREGATION
Meaning of SIGN OF AGGREGATION in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012