The Collaborative International Dictionary of English v.0.48:

Bracket \Brack"et\, n. [Cf. OF. braguette codpiece, F. brayette,
   Sp. bragueta, also a projecting mold in architecture; dim.
   fr. L. bracae breeches; cf. also, OF. bracon beam, prop,
   support; of unknown origin. Cf. Breeches.]
   [1913 Webster]
   1. (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.
      [1913 Webster]

   Note: This is the more general word. See Brace,
         Cantalever, Console, Corbel, Strut.
         [1913 Webster]

   2. (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.
      [1913 Webster]

   3. (Naut.) A shot, crooked timber, resembling a knee, used as
      a support.
      [1913 Webster]

   4. (Mil.) The cheek or side of an ordnance carriage.
      [1913 Webster]

   5. (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.
      [1913 Webster]

   6. A gas fixture or lamp holder projecting from the face of a
      wall, column, or the like.
      [1913 Webster]

   7. (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.
      [Webster 1913 Suppl.]

   Bracket light, a gas fixture or a lamp attached to a wall,
      column, etc.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bracket \Brack"et\, v. t. [imp. & p. p. Bracketed; p. pr. &
   vb. n. Bracketing]
   1. To place within brackets; to connect by brackets; to
      furnish with brackets.
      [1913 Webster]

   2. (Gunnery) To shoot so as to establish a bracket for (an
      object).
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

bracket
    n 1: a category falling within certain defined limits
    2: either of two punctuation marks (`<' or `>') used in computer
       programming and sometimes used to enclose textual material
       [syn: bracket, angle bracket]
    3: either of two punctuation marks ([ or ]) used to enclose
       textual material [syn: bracket, square bracket]
    4: a support projecting from a wall (as to hold a shelf) [syn:
       bracket, wall bracket]
    v 1: support with brackets; "bracket bookshelves"
    2: place into brackets; "Please bracket this remark" [syn:
       bracket, bracket out]
    3: classify or group

Moby Thesaurus II by Grady Ward, 1.0:

182 Moby Thesaurus words for "bracket":
   accouple, accumulate, advocate, agglutinate, ally, alpenstock,
   amass, analyze, apply, arm, articulate, assemble, associate,
   athletic supporter, back, backbone, backing, band, bandeau, bearer,
   bind, blood, bond, bra, brace, bracer, branch, brassiere, bridge,
   bridge over, buttress, cane, carrier, caste, category, cement,
   cervix, chain, clan, clap together, class, classification,
   classify, collate, collect, combine, comprise, concatenate,
   conglobulate, conjoin, conjugate, connect, console, contrast,
   copulate, corbel, correlate, corset, couple, couple up, cover,
   crook, crutch, decline, division, double-harness, double-team,
   draw a parallel, embrace, encompass, equate, estate,
   foundation garment, fulcrum, gather, girdle, glue, grade, group,
   grouping, guy, guywire, head, heading, hyphenate, identify,
   include, inflect, interrelate, jock, jockstrap, join, kin, knot,
   label, lay together, league, level, link, lump together, mainstay,
   maintainer, mark, marry, marshal, mass, mast, match, mate, merge,
   mobilize, neck, order, pair, pair off, parallel, parallelize,
   parenthesize, parse, piece together, pigeonhole, point, position,
   predicament, prop, punctuate, put together, race, rank, rating,
   reinforce, reinforcement, reinforcer, relate, relativize, rest,
   resting place, rigging, roll into one, rubric, section, sept, set,
   shelf, shoulder, shroud, solder, span, spine, splice, sprit, staff,
   standing rigging, station, status, stave, stay, stick,
   stick together, stiffener, strain, stratum, strengthener,
   subdivision, subgroup, suborder, support, supporter, sustainer,
   take in, tape, team, team up, tie, title, unify, unite, upholder,
   walking stick, wed, weld, yoke



The Free On-line Dictionary of Computing (30 December 2018):

bracket

    (Or square bracket) A left bracket or right
   bracket.

   Often used loosely for parentheses, square brackets,
   braces, angle brackets, or any other kind of unequal
   paired delimiters.

   (1996-09-08)