noun

• (curling) Movement of a moving rock away from a straight line.
• (weightlifting) Any exercise performed by bending the arm, wrist, or leg on the exertion against resistance, especially those that train the biceps.
  "Now do a curl and an overhead press, keeping your palms facing in."
• (calculus) The vector field denoting the rotationality of a given vector field.
  "The curl of the vector field #92;vec#123;F#125;(x,y,z) is the vector field #92;operatorname#123;curl#125;#92;,#92;vec#123;F#125;#92;equiv#92;vec#123;#92;nabla#125;#92;times#92;vec#123;F#125;#61;#92;left(#92;frac#123;#92;partialF#95;z#125;#123;#92;partialy#125;-#92;frac#123;#92;partialF#95;y#125;#123;#92;partialz#125;,#92;frac#123;#92;partialF#95;x#125;#123;#92;partialz#125;-#92;frac#123;#92;partialF#95;z#125;#123;#92;partialx#125;,#92;frac#123;#92;partialF#95;y#125;#123;#92;partialx#125;-#92;frac#123;#92;partialF#95;x#125;#123;#92;partialy#125;#92;right)."
• (calculus, proper noun) The vector operator, denoted rm curl; or ⃑∇×⃑(·), that generates this field.

verb

• (transitive) To cause to move in a curve.
  "He picked the ball up about forty yards out on the left wing, left a trail of Arsenal defenders in his wake, and curled the ball round Geoff Barnett as he came right out into the far corner."
• (transitive) To make into a curl or spiral.
  "She curls her spine; she wedges a pillow between her knees."
• (intransitive) To assume the shape of a curl or spiral.
  "It seemed to me that Mr. St. John's under lip protruded, and his upper lip curled a moment."
• (intransitive) To move in curves.
  "Clouds curled down from the mountains."