1. [n]  the act of preventing; "there was no bar against leaving"
2. [n]  a rigid piece of metal or wood; usually used as a fastening or obstruction of weapon; "there were bars in the windows to prevent escape"
3. [n]  an obstruction (usually metal) placed at the top of a goal; "it was an excellent kick but the ball hit the bar"
4. [n]  a counter where you can obtain food or drink; "he bought a hot dog and a coke at the bar"
5. [n]  (law) a railing that encloses the part of the courtroom where the judges and lawyers sit and the case is tried; "spectators were not allowed past the bar"
6. [n]  (British) a heating element in an electric fire; "an electric fire with three bars"
7. [n]  a room or establishment where alcoholic drinks are served over a counter; "he drowned his sorrows in whiskey at the bar"
8. [n]  a portable .30 caliber magazine-fed automatic rifle operated by gas pressure; used by United States troops in World Wars I and II and in the Korean War
9. [n]  a block of solid substance (such as soap or wax); "a bar of chocolate"
10. [n]  musical notation for a repeating pattern of musical beats; "the orchestra omitted the last twelve bars of the song"
11. [n]  the body of individuals qualified to practice law in a particular jurisdiction; "he was admitted to the bar in New Jersey"
12. [n]  a submerged (or partly submerged) ridge in a river or along a shore; "the boat ran aground on a submerged bar in the river"
13. [n]  (meteorology) a unit of pressure equal to a million dynes per square centimeter; "unfortunately some writers have used bar for one dyne per square centimeter"
14. [v]  prevent from entering; keep out; "He was barred from membership in the club"
15. [v]  secure with, or as if with, bars; "He barred the door"
16. [v]  render unsuitable for passage; "block the way"; "barricade the streets"
17. [v]  expel, as if by official decree; "he was banished from his own country"

BAR is a 3 letter word that starts with B.

1. \Bar\ (b[aum]r), n. [OE. barre, F. barre, fr. LL. barra, W.
   bar the branch of a tree, bar, baren branch, Gael. & Ir.
   barra bar. [root]91.]
   1. A piece of wood, metal, or other material, long in
      proportion to its breadth or thickness, used as a lever
      and for various other purposes, but especially for a
      hindrance, obstruction, or fastening; as, the bars of a
      fence or gate; the bar of a door.
            Thou shalt make bars of shittim wood. --Ex. xxvi.
                                                  26.
   2. An indefinite quantity of some substance, so shaped as to
      be long in proportion to its breadth and thickness; as, a
      bar of gold or of lead; a bar of soap.
   3. Anything which obstructs, hinders, or prevents; an
      obstruction; a barrier.
            Must I new bars to my own joy create? --Dryden.
   4. A bank of sand, gravel, or other matter, esp. at the mouth
      of a river or harbor, obstructing navigation.
   5. Any railing that divides a room, or office, or hall of
      assembly, in order to reserve a space for those having
      special privileges; as, the bar of the House of Commons.
   6. (Law)
      (a) The railing that incloses the place which counsel
          occupy in courts of justice. Hence, the phrase at the
          bar of the court signifies in open court.
      (b) The place in court where prisoners are stationed for
          arraignment, trial, or sentence.
      (c) The whole body of lawyers licensed in a court or
          district; the legal profession.
      (d) A special plea constituting a sufficient answer to
          plaintiff's action.
   7. Any tribunal; as, the bar of public opinion; the bar of
      God.
   8. A barrier or counter, over which liquors and food are
      passed to customers; hence, the portion of the room behind
      the counter where liquors for sale are kept.
   9. (Her.) An ordinary, like a fess but narrower, occupying
      only one fifth part of the field.
   10. A broad shaft, or band, or stripe; as, a bar of light; a
       bar of color.
   11. (Mus.) A vertical line across the staff. Bars divide the
       staff into spaces which represent measures, and are
       themselves called measures.
   Note: A double bar marks the end of a strain or main division
         of a movement, or of a whole piece of music; in
         psalmody, it marks the end of a line of poetry. The
         term bar is very often loosely used for measure, i.e.,
         for such length of music, or of silence, as is included
         between one bar and the next; as, a passage of eight
         bars; two bars' rest.
   12. (Far.) pl.
       (a) The space between the tusks and grinders in the upper
           jaw of a horse, in which the bit is placed.
       (b) The part of the crust of a horse's hoof which is bent
           inwards towards the frog at the heel on each side,
           and extends into the center of the sole.
   13. (Mining)
       (a) A drilling or tamping rod.
       (b) A vein or dike crossing a lode.
   14. (Arch.)
       (a) A gatehouse of a castle or fortified town.
       (b) A slender strip of wood which divides and supports
           the glass of a window; a sash bar.
   {Bar shoe} (Far.), a kind of horseshoe having a bar across
      the usual opening at the heel, to protect a tender frog
      from injury.
   {Bar shot}, a double headed shot, consisting of a bar, with a
      ball or half ball at each end; -- formerly used for
      destroying the masts or rigging in naval combat.
   {Bar sinister} (Her.), a term popularly but erroneously used
      for baton, a mark of illegitimacy. See {Baton}.
   {Bar tracery} (Arch.), ornamental stonework resembling bars
      of iron twisted into the forms required.
   {Blank bar} (Law). See {Blank}.
   {Case at bar} (Law), a case presently before the court; a
      case under argument.
   {In bar of}, as a sufficient reason against; to prevent.
   {Matter in bar}, or {Defence in bar}, a plea which is a final
      defense in an action.
   {Plea in bar}, a plea which goes to bar or defeat the
      plaintiff's action absolutely and entirely.
   {Trial at bar} (Eng. Law), a trial before all the judges of
      one the superior courts of Westminster, or before a quorum
      representing the full court.
   

2. \Bar\ (b[aum]r), v. t. [imp. & p. p. {Barred} (b[aum]rd); p.
   pr. & vb. n. {Barring}.] [ F. barrer. See {Bar}, n.]
   1. To fasten with a bar; as, to bar a door or gate.
   2. To restrict or confine, as if by a bar; to hinder; to
      obstruct; to prevent; to prohibit; as, to bar the entrance
      of evil; distance bars our intercourse; the statute bars
      my right; the right is barred by time; a release bars the
      plaintiff's recovery; -- sometimes with up.
            He barely looked the idea in the face, and hastened
            to bar it in its dungeon.             --Hawthorne.
   3. To except; to exclude by exception.
            Nay, but I bar to-night: you shall not gauge me By
            what we do to-night.                  --Shak.
   4. To cross with one or more stripes or lines.
            For the sake of distinguishing the feet more
            clearly, I have barred them singly.   --Burney.
   

1. /bar/ The second metasyntactic variable, after foo and before baz. E.g. "Suppose function FOO calls functions BAR..."

2. Often appended to foo to produce foobar.

[jargon file]

used to denote the means by which a door is bolted (Neh. 3:3); a rock in the sea (Jonah 2:6); the shore of the sea (Job 38:10); strong fortifications and powerful impediments, etc. (Isa. 45:2; Amos 1:5); defences of a city (1 Kings 4:13). A bar for a door was of iron (Isa. 45:2), brass (Ps. 107:16), or wood (Nah. 3:13).