Note on the Terminology Convex and Concave.

The article recommends to standardize the terms convex and concave which economists use in their descriptions of curves. A uniform language has great advantages although nomenclature is a matter of convention and taste. These three expressions are commonly found. Curves are (a) concave or convex "to the origin"; (b) concave or convex "upward" or "downward"; (c) concave or convex "from above" or "from below." Except in very few cases of minor importance for economists the article suggests that the terminology convex or concave from above is the clearest, simplest and most generally used.