The adjective viscid is used to describe something that is sticky or a thick, slow-moving liquid. If you bake bread and you get flour all over your counters, clean it up carefully because adding water can turn the flour into a viscid paste, and then you'll really have a mess!
The word viscid is from the Latin word viscum, or birdlime. Birdlime is a sticky substance made from sap and is smeared on branches. Small birds land on the branches and are trapped, allowing someone to easily catch them. The word viscous comes from the same root and has a similar meaning — think of lava and how it moves slowly and thickly down a mountain.