A heap is a messy pile of things stacked or thrown together without much order or care. You might see a heap of dirty laundry on your bedroom floor, a heap of leaves raked into the corner of the yard, or a heap of books tumbled onto your desk. The word suggests disorder: things in a heap aren't neatly arranged or organized, they're just piled up wherever they landed.

The word also means a large amount of something. If your friend has heaps of baseball cards, she has way more than just a few. When someone says “Thanks a heap,” they mean “Thanks a lot,” though sometimes people say this sarcastically when they're not actually thankful.

As a verb, to heap means to pile things up, often generously or abundantly. A cafeteria worker might heap mashed potatoes onto your plate. You could heap praise on a friend who helped you study, meaning you give them lots of compliments and thanks. The verb suggests piling on more and more, not measuring carefully or holding back.