B1 Something that is thick is larger than usual between its opposite sides: a thick layer of snow → Opposite thin adj
› used to say how long the distance is from one side of something to the other: a piece of wood 6 inches thick
B1 growing very close together and in large amounts: thick, dark hair
› Thick smoke, cloud, or fog is difficult to see through: Thick, black smoke was pouring out of the chimney.
› UK informal not intelligent