His glasses have a concave lens.
The melon was so rotten that it became concave when it was pressed on.
shield
The concave mirror reflected the light inwards, creating a magnified image of the object.
A concave lens is thinner at the centre. People who are short sighted often use a concave lens to help them see better.
concave lens :P
A concave lens is used to correct nearsightedness by diverging light rays before they reach the eye, helping to focus images properly on the retina.
I use my concave dish for the purpose of panning for gold dust on nugget
He held his spoon upside down so that its concave side for holding his soup was rendered useless.
The opposite of convex is concave. Concave shapes have an inward curve, while convex shapes have an outward curve.
plano concave
Concave, because you can connect the corners from the outside.
Concave is a property of [irregular] polygons. A parallelogram cannot be concave.