bracket

A punctuation mark, like ( ) or [ ], used to enclose text.

"Put the optional information in brackets."

A category or group of people or things within defined limits.

"He is in the highest tax bracket."

A projecting support, often L-shaped, for a shelf or light fixture.

"The shelf was held up by metal brackets."

To group or classify together, or enclose within brackets.

"We can bracket these two ideas together."