Definition of stack:
a large pile of hay, grain, straw, or the like, larger at the bottom than the top, sometimes covered with thatch
; a pile of similar objects, each directly on top of the last
"please bring me a chair from that stack in the corner."
to place one or more objects or material in the form of a stack or on an existing stack; to arrange the cards in a deck in a particular manner
"please stack those chairs in the corner."