Merriam-Webster's Collegiate® Dictionary, 11th Edition
BRACKET
I. noun see: breech
Date: 1580
an overhanging member that projects from a structure (as a wall) and is usually designed to support a vertical load or to strengthen an angle, a fixture (as for holding a lamp) projecting from a wall or column,
3. one of a pair of marks [ ] used in writing and printing to enclose matter or in mathematics and logic as signs of aggregation, one of the pair of marks < > used to enclose matter, parenthesis 3, brace 5b, a section of a continuously numbered or graded series (as age ranges or income levels),
II. transitive verb
Date: circa 1847
1. to place within or as if within brackets , to eliminate from consideration , to extend around so as to encompass ; include , to furnish or fasten with brackets, to put in the same category or group ,
4. to get the range on (a target) by firing over and short , to establish the limits of , to take photographs of at more than one exposure in order to ensure that the desired exposure is obtained