معنی کلمه :‌ indention

Same as Indentation, 4.

Any one of numerous rays of the family Dasyatidæ, syn. Trygonidæ, having one or more large sharp barbed dorsal spines, on the whiplike tail, capable of inflicting severe wounds. Some species reach a large size, and some, esp., on the American Pacific coast, are very destructive to oysters.