adj., n., & adv.
adj. 1 a of great or specified extent between opposite surfaces (a thick wall; a wall two metres thick). b of large diameter (a thick rope). 2 a (of a line etc.) broad; not fine. b (of script or type, etc.) consisting of thick lines. 3 a arranged closely; crowded together; dense. b numerous (fell thick as peas). 4 (usu. foll. by with) densely covered or filled (air thick with snow). 5 a firm in consistency; containing much solid matter; viscous (a thick paste; thick soup). b made of thick material (a thick coat). 6 muddy, cloudy; impenetrable by sight (thick darkness). 7 colloq. (of a person) stupid, dull. 8 (of a voice) indistinct. 9 colloq. intimate or very friendly (esp. thick as thieves).
n. a thick part of anything.
adv. thickly (snow was falling thick; blows rained down thick and fast). a bit thick Brit. colloq. unreasonable or intolerable. in the thick of 1 at the busiest part of. 2 heavily occupied with. thick ear Brit. sl. the external ear swollen as a result of a blow (esp. give a person a thick ear). thick-skinned not sensitive to reproach or criticism. thick-skulled (or -witted) stupid, dull; slow to learn. through thick and thin under all conditions; in spite of all difficulties. thickish adj. thickly adv.
[ OE thicce (adj. & adv.) f. Gmc ]