Expandable means capable of being made larger or extended. An expandable suitcase has a zipper that lets you increase its size when you need to pack more clothes. An expandable table has leaves you can insert to make it longer for holiday dinners when extra family members visit.

Many things are designed to be expandable because needs change. A phone's storage might be expandable with a memory card. A business might rent expandable office space that can grow as more employees join. Video game worlds are often expandable through downloadable content that adds new levels or characters.

The word emphasizes potential: something expandable can grow when needed, even if it's currently small. That makes it different from something that's simply large. A backpack might be expandable with extra compartments that zip open, making it more versatile than a bigger but fixed-size bag.

You'll also hear the related word expansible, which means essentially the same thing, though expandable is more common in everyday speech.