English definition of “pocket”
/ˈpɒkɪt/ noun [C]
BAG › a small bag that is sewn or fixed onto or into a piece of clothing, a bag, the back of a seat, etc: a coat/shirt/trouser pocket He was asked to empty his pockets. Safety instructions are in the pocket on the seat in front of you.
SMALL AREA/AMOUNT › a small area or small amount of something that is different from what is around it: There was real poverty in some pockets of the country. small pockets of air trapped inside the glass
MONEY › the amount of money that you have for spending: I shouldn't have to pay for travel out of my own pocket (= with my own money).
be out of pocket › to have less money than you should have because you have paid for something: The holiday company cancelled our trip and we were left hundreds of pounds out of pocket.