scalar curl

Etymology
From +.

Noun

 * 1)  The coefficient of k in the three-dimensional curl of a two-dimensional vector field.
 * Since the curl of the vector field $$\vec{F}=(xy,xy,0)$$ is the vector field $$\vec{\nabla}\times\vec{F}=(0,0,y-x)$$, the scalar curl of the vector field $$\vec{G}=(xy,xy)$$ is the scalar field $$y-x\;$$.