Definition of pocket:
(n) :
a
bag stitched to an item of clothing, used for carrying small items; a net or similar struture at each corner, and halfway along the edge, of a
billiard table into which balls are to be struck
"the drilling expedition discovered a pocket of natural gas."
(v) :
to put (something) into a pocket; to cause a ball to go into one of the pockets of the table
(adj) :
of a size suitable for putting into a pocket
"pocket dictionary"