verb

• (intransitive) To move gently and vertically, in either a single motion or repeatedly up and down, at or near the surface of a body of water, or similar medium.
  "The cork bobbed gently in the calm water."
• (transitive) To move (something) as though it were bobbing in water.
  "I bobbed my head underwater and saw the goldfish."
• (transitive) To move (something) as though it were bobbing in water.
  "She bobbed on his knob."
• (intransitive) Synonym of blob (“catch eels using worms strung on thread”).
  "After they had had supper Frank said, Do you remember those men whom we saw near Norwich, who sat in small boats all the night long, and with a line in each hand, bobbed for eels?"

noun

• (obsolete) A knot or short curl of hair; also, a bob wig.
  "A plain brown bob he wore."
• (obsolete) The refrain of a song.
  "Ay, Ay, and Then to Bed, ſays the Bride. This Girl did but ſpeak the Widows Mind; for let Fleſh and Blood pretend what it will, to Bed, to Bed, will be the Bob of the Song."
• (obsolete) A jeer; a sharp jest or taunt.
  "Hee, that a Foole doth very wiſely hit, Doth very fooliſhly, although he ſmart, Seeme ſenſeleſſe of the bob."

verb

• (transitive) To cut (hair) into a bob haircut.
  "I got my hair bobbed. How do you like it?"
• (transitive) To shorten by cutting; to dock; to crop.

noun

• (Kenya, slang; UK and Australia, historical, dated) A shilling.
  "One of the bottlenosed fraternity it was went by the name of James Wought alias Saphiro alias Spark and Spiro, put an ad in the papers saying he'd give a passage to Canada for twenty bob."
• (Australia, dated slang) A 10-cent coin.
• (slang) An unspecified amount of money.
  "Spot me a few bob, Robert."