(chek), n. [OE. cheke, cheoke, AS. ceàce, ceòce; cf. Goth. kukjan to kiss, D. kaak cheek; perh. akin to E. chew, jaw.] 1. The side of the face below the eye. 2. The cheek bone. [Obs.] Caucer. 3.pl.(Mech.) Those pieces of a machine, or of any timber, or stone work, which form corresponding sides, or which are similar and in pair; as the cheeks (jaws) of a vise; the cheeks of a gun carriage, etc. 4.pl. The branches of a bridle bit. Knight. 5.(Founding) A section of a flask, so made that it can be moved laterally, to permit the removal of the pattern from the mold; the middle part of a flask. 6. Cool confidence; assurance; impudence. [Slang] Cheek of beef. See Illust. of Beef. — Cheek bone(Anat.) the bone of the side of the face; esp., the malar bone. — Cheek by jowl, side by side; very intimate. — Cheek pouch(Zoöl.), a sacklike dilation of the cheeks of certain monkeys and rodents, used for holding food. — Cheeks of a block, the two sides of the shell of a tackle block. — Cheeks of a mast, the projection on each side of a mast, upon which the trestletrees rest. — Cheek tooth(Anat.), a hinder or molar tooth. — Butment cheek. See under Butment.