curl / kərl/ • v. 1. form or cause to form into a curved or spiral shape: [intr.] her fingers curled around the microphone [tr.] she used to curl her hair with rags. ∎  [intr.] (curl up) sit or lie with the knees drawn up. ∎  move or cause to move in a spiral or curved course: [intr.] a wisp of smoke curling across the sky. ∎  (with reference to one's mouth or upper lip) raise or cause to raise slightly on one side as an expression of contempt or disapproval: [intr.] Maria saw his lip curl sardonically. ∎  (in weight training) lift (a weight) using only the hands, wrists, and forearms.2. [intr.] play at the game of curling.• n. 1. a lock of hair having a spiral or coiled form. ∎  a thing having a spiral or inwardly curved form. ∎  a curling movement. ∎  (with reference to a person's hair) a state or condition of being curled. ∎ see leaf curl. ∎  a weightlifting exercise involving movement of only the hands, wrists, and forearms.2. Math. the vector product of the operator del and a given vector.

curl twist or form into ringlets. First recorded (XIV) in pp. crolled, crulled, extended form with -ED 1 of ME. crolle, crulle — MDu. krul ( = MHG. krol) curly, prob. rel. to MLG. krūs crisp, curly (G. kraus curled).
Hence curl sb. XVII; whence curly (see -Y 1) XVIII.