symmetry of top left with bottom right, and top right with bottom left
adjective 1. (postpositive) (Brit, informal) not straight; askew
noun, plural skis or, sometimes, ski. 1. one of a pair of long, slender runners made of wood, plastic, or metal used in gliding over snow. 2. water ski. verb (used without object), skied, skiing. 3. to travel on skis, as for sport. verb (used with object), skied, skiing. 4. to use skis on; travel […]
skia- pref. Shadow: skiascopy.
noun 1. a picture made by outlining and shading a subject’s shadow. 2. skiagraph.