Definition of "Thumb" :

noun: a convex molding having a cross section in the form of a quarter of a circle or of an ellipse

noun: the part of a glove that provides a covering for the thumb

noun: the thick short innermost digit of the forelimb

verb: feel or handle with the fingers

verb: travel by getting free rides from motorists

verb: look through a book or other written material

"He thumbed through the report."