1. [n]  a short abrupt inclination (as of the head); "he gave me a short bob of acknowledgement"
2. [n]  a short or shortened tail of certain animals
3. [n]  a small float usually made of cork; attached to a fishing line
4. [n]  a hanging weight, especially a metal ball on a string
5. [n]  a long racing sled (for 2 or more people) with a steering mechanism
6. [n]  a hair style for women and children; a short haircut all around
7. [n]  a former monetary unit in Great Britain
8. [v]  cut hair in the style of a bob; "Bernice bobs her hair these days!"
9. [v]  make a curtsy; usually done only by girls and women; as a sign of respect; "She curtsied when she shook the Queen's hand"
10. [v]  remove or shorten the tail of an animal
11. [v]  move up and down repeatedly; "her rucksack bobbed gently on her back"
12. [v]  ride a bobsled; "The boys bobbed down the hill screaming with pleasure"

Bob
Bob

more details ...

1. \Bob\, n. [An onomatopoetic word, expressing quick, jerky
   motion; OE. bob bunch, bobben to strike, mock, deceive. Cf.
   Prov. Eng. bob, n., a ball, an engine beam, bunch, blast,
   trick, taunt, scoff; as, a v., to dance, to courtesy, to
   disappoint, OF. bober to mock.]
   1. Anything that hangs so as to play loosely, or with a short
      abrupt motion, as at the end of a string; a pendant; as,
      the bob at the end of a kite's tail.
            In jewels dressed and at each ear a bob. --Dryden.
   2. A knot of worms, or of rags, on a string, used in angling,
      as for eels; formerly, a worm suitable for bait.
            Or yellow bobs, turned up before the plow, Are
            chiefest baits, with cork and lead enow. --Lauson.
   3. A small piece of cork or light wood attached to a fishing
      line to show when a fish is biting; a float.
   4. The ball or heavy part of a pendulum; also, the ball or
      weight at the end of a plumb line.
   5. A small wheel, made of leather, with rounded edges, used
      in polishing spoons, etc.
   6. A short, jerking motion; act of bobbing; as, a bob of the
      head.
   7. (Steam Engine) A working beam.
   8. A knot or short curl of hair; also, a bob wig.
            A plain brown bob he wore.            --Shenstone.
   9. A peculiar mode of ringing changes on bells.
   10. The refrain of a song.
             To bed, to bed, will be the bob of the song.
                                                  --L'Estrange.
   11. A blow; a shake or jog; a rap, as with the fist.
   12. A jeer or flout; a sharp jest or taunt; a trick.
             He that a fool doth very wisely hit, Doth very
             foolishly, although he smart, Not to seem senseless
             of the bob.                          --Shak.
   13. A shilling. [Slang, Eng.] --Dickens.
   

2. \Bob\, v. t. [imp. & p. p. {Bobbed}; p. pr. & vb. n.
   {Bobbing}.] [OE. bobben. See {Bob}, n.]
   1. To cause to move in a short, jerking manner; to move (a
      thing) with a bob. ``He bobbed his head.'' --W. Irving.
   2. To strike with a quick, light blow; to tap.
            If any man happened by long sitting to sleep . . .
            he was suddenly bobbed on the face by the servants.
                                                  --Elyot.
   3. To cheat; to gain by fraud or cheating; to filch.
            Gold and jewels that I bobbed from him. --Shak.
   4. To mock or delude; to cheat.
            To play her pranks, and bob the fool, The shrewish
            wife began.                           --Turbervile.
   5. To cut short; as, to bob the hair, or a horse's tail.
   

3. \Bob\, v. i.
   1. To have a short, jerking motion; to play to and fro, or up
      and down; to play loosely against anything. ``Bobbing and
      courtesying.'' --Thackeray.
   2. To angle with a bob. See {Bob}, n., 2 & 3.
            He ne'er had learned the art to bob For anything but
            eels.                                 --Saxe.
   {To bob at an apple}, {cherry}, etc. to attempt to bite or
      seize with the mouth an apple, cherry, or other round
      fruit, while it is swinging from a string or floating in a
      tug of water.
   

David Betz. A tiny object-oriented language.

[Dr Dobbs J, Sep 1991, p.26].