DISTANCE › Something that is thick is larger than usual between its opposite sides: a thick slice of meat a thick layer of snow
10cm/2m, etc thick › being 10cm/2m, etc thick: a piece of wood 2cm thick
LARGE AMOUNT › growing very close together and in large amounts: thick, dark hair
SMOKE › Thick smoke, cloud, or fog is difficult to see through: Thick, black smoke was pouring out of the chimney.
LIQUID › A thick substance or liquid has very little water in it and does not flow easily: Stir the sauce over a low heat until thick.
STUPID UK informal › not intelligent
be thick with sth › If something is thick with a particular substance, it is covered in or full of that substance: The air was thick with petrol fumes. → See also have (a) thick skin