Jelly is a sweet, wobbly food made by boiling fruit juice with sugar and a substance called pectin that makes it set into a soft, spreadable form. When you open a jar of grape jelly and spread it on toast, you're using fruit that's been transformed into a smooth, gel-like treat. Jelly is clear or translucent, unlike jam, which contains chunks of fruit.

The word also describes anything with that characteristic wobbly, gel-like texture. When you make Jell-O and it jiggles on your plate, that's jelly. Jellyfish get their name from their soft, jelly-like bodies. If your legs feel weak and unstable after a long run, you might say they've turned to jelly.

In science, scientists might grow bacteria on a jelly-like substance in a petri dish. The consistency of jelly, somewhere between liquid and solid, makes it useful for many purposes beyond food.

Outside North America, particularly in Britain, people use “jelly” to mean what Americans call Jell-O or gelatin dessert. So if a British friend invites you for jelly and ice cream, they're not offering fruit spread, but a wobbly dessert!