Stacked wilds is a term most often used by video slot and slot machine players, and it describes a bonus feature present in some slot games.
If you have played video slots before, chances are you are familiar with wild symbols and their function. In virtually every video slot, they act as a replacement and can substitute for every other symbol. When it comes to stacked wilds, they pretty much have the same function. The only difference between a regular wild symbol and stacked wilds is that stacked wilds come, well, stacked.
In other words, instead of taking one spot on the reels, stacked wilds come in pairs of two or three, and in some cases, they can even cover an entire reel. For this reason, stacked wilds can provide significantly bigger payouts than regular wilds and can net you multiple wins during a single spin.