What does Concave Mean?
The word concave means a surface that curves inwards much like the inner surface of a circle or sphere. Besides this there are also two other places where on earth the word concave can be found both related to mathematics, namely in geometry and calculus. The primary meaning however of the word is concerned next to the inward curving shape of objects. The word is from the Latin word “concavus” which means something like “intensive hollow”. It can be traced back further and is believed to enjoy indo European roots. In optics Concave is a kind of lens that is used to deflect light. It is used to externally correct discouraging vision. It is the exact opposite of a convex lens which is like the external surface of a circle. Depending on the type of mirage deformity a concave lens can be a convex-concave, meniscus (greater curve), and Plano concave or biconcave lens.
