Meaning

• (heading) A pile.

• A smokestack.

• (heading) In computing.

• A generalization of schemes in algebraic geometry and of sheaves.

• A coastal landform, consisting of a large vertical column of rock in the sea.

• (library) Compactly spaced bookshelves used to house large collections of books.

• A large amount of an object.

  "They paid him a stack of money to keep quiet."

• A pile of rifles or muskets in a cone shape.

• The amount of money a player has on the table.

• (heading) In architecture.

• A fall or crash, a prang.

• A blend of various dietary supplements or anabolic steroids with supposed synergistic benefits.

• A holding pattern, with aircraft circling one above the other as they wait to land.

• The quantity of a given item which fills up an inventory slot or bag.

  "I've got 107 Golden Branches, but the stack size is 20 so they're taking up 6 spaces in my inventory."

Meaning

• To arrange in a stack, or to add to an existing stack.

  "Please stack those chairs in the corner."

• To arrange the cards in a deck in a particular manner.

  "This is the third hand in a row where you've drawn four of a kind. Someone is stacking the deck!"

• To take all the money another player currently has on the table.

  "I won Jill's last $100 this hand; I stacked her!"

• To deliberately distort the composition of (an assembly, committee, etc.).

  "The Government was accused of stacking the parliamentary committee."

• To crash; to fall.

  "Jim couldn′t make it today as he stacked his car on the weekend."

• To operate cumulatively.

  "A magical widget will double your mojo. And yes, they do stack: if you manage to get two magical widgets, your mojo will be quadrupled. With three, it will be octupled, and so forth."

• To place (aircraft) into a holding pattern.

• To collect precious metal in the form of various small objects such as coins and bars.