Definition of thumbs:
(n) :
The shortest and thickest digit of the hand that for humans has the most mobility and can be made to oppose (moved to touch) all of the other fingers.
(v) :
(transitive) To touch or cover with the thumb.
(v) :
To manipulate (an object) with the thumb; especially, to pull back the hammer or open the cylinder of a revolver.
(n) :
(graphical user interface) The part of a slider that may be moved linearly along the slider.
(n) :
(colloquial, Internet) A thumbnail picture.
(v) :
(transitive, with through) To turn the pages of (a book) in order to read it cursorily.