To congeal means to change from liquid to solid, usually by cooling. When hot bacon grease sits in a pan after breakfast, it congeals into a white, waxy solid. When blood from a cut is exposed to air, it congeals into a clot that helps stop the bleeding. Jello congeals in the refrigerator, transforming from sweet liquid into a wiggly solid.

The word often describes something becoming thick, sticky, or less fluid in an unpleasant way. Leftover gravy congeals into a gloppy mess if you leave it out too long. Old paint can congeal in the can if the lid isn't sealed properly.

Scientists might describe how molecules in a liquid slow down and lock together as temperature drops, causing the substance to congeal. But you don't need to be a scientist to notice congealing. Just watch what happens to melted chocolate or warm honey as it cools. The process happens naturally all around us, turning liquids into solids through temperature change or time.