WordReference Random House Unabridged Dictionary of American English © 2024square′ brack′et, - Printingbracket (def. 3).
Collins Concise English Dictionary © HarperCollins Publishers::
square bracket n - either of a pair of characters [ ], used to enclose a section of writing or printing to separate it from the main text
- Also called: bracket either of these characters used as a sign of aggregation in mathematical or logical expressions indicating that the expression contained in the brackets is to be evaluated first and treated as a unit in the evaluation of the whole