What is the meaning of thumb?

noun

• The thick short innermost digit of the forelimb.
  • synonyms: pollex
• The part of a glove that provides a covering for the thumb.
• A convex molding having a cross section in the form of a quarter of a circle or of an ellipse.
  • synonyms: ovolo, quarter round

verb

• Travel by getting free rides from motorists.
  • synonyms: hitchhike, hitch
• Look through a book or other written material.
  • usage: "He thumbed through the report"; "She leafed through the volume"
  • synonyms: flick, flip, riffle, leaf, riff
• Feel or handle with the fingers.
  • usage: "finger the binding of the book"
  • synonyms: finger