The stack is a sum of money or of other equally liquid financial assets. The stack only goes up or down and it's your main job to make it go up. The stack is your. This Slang page is designed to explain what the meaning of stacks is. The slang word / phrase / acronym stacks means . Online Slang Dictionary. A list of slang. stack meaning, definition, what is stack: a pile of things arranged one on top of another. Learn more. Stack up · “stack” - English Dictionary · Stack the cards idiom · Stack system.