Viscid describes something thick, sticky, and slow to flow — the texture of syrup, tree sap, or the film left on a leaf. It is a rare, bookish word. In everyday English you would say sticky, gooey, or thick; in scientific writing you would more often say viscous. The difference between viscid and viscous is worth knowing, even though many writers treat them as the same. Viscous is the standard word in physics and engineering, and it is about resistance to flowing: viscous oil, high-viscosity fluid. Viscid leans toward the feel of the thing when you touch it — the clinging, adhesive quality. Botanists use it in exactly this way to describe leaves or stems coated in a sticky substance. Outside botany the two words overlap so much that you can usually read viscid as "viscous" and lose nothing. It carries a slightly unpleasant edge. A viscid liquid sounds like something you would rather not put your hand in. Writers who want that feeling choose it on purpose.

黏稠的、黏黏的。台灣中文說「黏稠」「黏答答」。這個字很罕見，實際上多半會用 viscous（黏性的、黏滯的）；viscid 偏重「摸起來會黏手」的感覺。