Koilonychia vs. Concavity

Koilonychianoun

A deformity of the nails characterized by concavity of the outer surface

Concavitynoun

(uncountable) The state of being concave

Koilonychia

Koilonychia, also known as spoon nails,: 782  is a nail disease that can be a sign of hypochromic anemia, especially iron-deficiency anemia.: 656  It refers to abnormally thin nails (usually of the hand) which have lost their convexity, becoming flat or even concave in shape. In a sense, koilonychia is the opposite of nail clubbing.

Concavitynoun

(countable) A concave structure or surface

Concavitynoun

A concave surface, or the space bounded by it; the state of being concave.

Concavitynoun

a shape that curves or bends inward

Concavitynoun

the property possessed by a concave shape