thick

Concise Oxford English Dictionary © 2008 Oxford University Press:
thick/θɪk/

▶adjective

• 1 with opposite sides or surfaces relatively far apart.

  ■ (of a garment or similar item) made of heavy material.

• 2 made up of a large number of things or people close together.

  ■ (thick with) densely filled or covered with.

  ■ (of the air or atmosphere, or a substance in the air) opaque, heavy, or dense: thick fog.

• 3 (of a liquid or a semi-liquid substance) relatively firm in consistency; not flowing freely.

• 4 informal of low intelligence; stupid.

• 5 (of a voice) hoarse or husky.

  ■ (of an accent) very marked and difficult to understand.

• 6 informal having a very close, friendly relationship.

▶noun (the thick) the middle or the busiest part of something: in the thick of battle. ▶adverb thickly: bread spread thick with butter.

– phrases
be thick on the ground see ground1.
a bit thick Brit. informal unfair or unreasonable.
give someone (or get) a thick ear Brit. informal punish someone (or be punished) with a blow on the ear.
have a thick skin see skin.
thick and fast rapidly and in great numbers.
(as) thick as thieves informal very close or friendly.
(as) thick as two (short) planks (or as a plank) Brit. informal very stupid.
through thick and thin under all circumstances, no matter how difficult.

– derivatives
thickish adjective,
thickly adverb.

– origin OE thicce, of Gmc origin.