bracket

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A simple rigid structure in the shape of an L, one arm of which is fixed to a vertical surface, the other projecting horizontally to support a shelf or other weight.
• noun A small shelf or shelves supported by such structures.
• noun Architecture A decorative or weight-bearing structural unit, two sides of which form a right angle with one arm flush against a wall and the other flush beneath a projecting surface, such as eaves or a bay window.
• noun A wall-anchored fixture for gas or electricity.
• noun A square bracket.
• noun An angle bracket.
• noun Chiefly British One of a pair of parentheses.
• noun A classification or grouping, especially within a sequence of numbers or grades, as a category of incomes sharing the same tax rate.
• noun The distance between two impacting shells, the first aimed beyond a target and the second aimed short of it, used to determine the range for artillery fire.
• noun The shells fired in such a manner.
• transitive verb To furnish or support with a bracket or brackets.
• transitive verb To place within or as if within brackets.
• transitive verb To classify or group together.
• transitive verb To include or exclude by establishing specific boundaries.
• transitive verb To fire beyond and short of (a target) in order to determine artillery range.

from The Century Dictionary.

• To furnish with or support by a bracket or brackets; in writing and printing, to place within brackets.
• To place on or within the same bracket or brackets; join or mention together as coequal or correlative; connect by or as if by a printers' brace: as, the names of Smith and Jones are bracketed, or bracketed together, as candidates.
• noun Same as bragget.
• Brackish; salt; briny: as, “living upon beef and brack water.”
• noun A supporting piece or combination of pieces of moderate projection, generally springing from a vertical surface.
• noun A gas-pipe with a burner, and often a support for a shade or globe, projecting from a wall or pillar.
• noun In gunnery, the cheek of a mortar-carriage, made of strong planking.
• noun One of two marks [ ], formerly called crotchets, used to inclose a note, reference, explanation, or the like, and thus separate it from the context; sometimes, also, one of a pair of braces { } similarly used, or a single brace { used to couple two or more lines or names.
• noun The position of being classed or bracketed with another or others.
• noun A name given to a head-dress of the fourteenth century.
• noun In mining, the platform over the mouth of a shaft.
• noun In carriages, a heavy standard placed at an incline at the front end of the boot of a coach as a support for the foot-board.
• noun A stiffening-rib on a casting.
• noun In wood ship-building, a short crooked timber, resembling a knee, for support or ornament.
• noun In iron ship-building, a piece of plate of a triangular shape uniting, at their junction, two parts which meet at an angle to strengthen the joint against flexure.
• In ship-building, to unite by a bracket.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Arch.) An architectural member, plain or ornamental, projecting from a wall or pier, to support weight falling outside of the same; also, a decorative feature seeming to discharge such an office.
• noun (Engin. & Mech.) A piece or combination of pieces, usually triangular in general shape, projecting from, or fastened to, a wall, or other surface, to support heavy bodies or to strengthen angles.
• noun (Naut.) A shot, crooked timber, resembling a knee, used as a support.
• noun (Mil.) The cheek or side of an ordnance carriage.
• noun (Print.) One of two characters [], used to inclose a reference, explanation, or note, or a part to be excluded from a sentence, to indicate an interpolation, to rectify a mistake, or to supply an omission, and for certain other purposes; -- called also crotchet.
• noun A gas fixture or lamp holder projecting from the face of a wall, column, or the like.
• noun (Gunnery) A figure determined by firing a projectile beyond a target and another short of it, as a basis for ascertaining the proper elevation of the piece; -- only used in the phrase, to establish a bracket. After the bracket is established shots are fired with intermediate elevations until the exact range is obtained. In the United States navy it is called fork.
• noun a gas fixture or a lamp attached to a wall, column, etc.
• transitive verb To place within brackets; to connect by brackets; to furnish with brackets.
• transitive verb (Gunnery) To shoot so as to establish a bracket for (an object).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A fixture attached to a wall to hold up a shelf.
• noun engineering Any intermediate object that connects a smaller part to a larger part, the smaller part typically projecting sideways from the larger part.
• noun "(" and ")" specifically, the other forms above requiring adjectives for disambiguation.
• noun One of several ranges of numbers.
• verb To bound on both sides, to surround as enclosing with brackets.