A readability metric for English writing, estimating how many years of formal education a person needs in order to understand the text on the first reading. It is based on the average sentence length and the proportion of words of three or more syllables.

(meteorology, physiology) A measure of the reaction of the human body to a combination of heat and humidity.

(UK, economics) A measure of inflation based on the changing cost of a representative sample of retail goods and services. Calculated on a slightly different basis to the Consumer Price Index.

(economics) An index created by the World Bank, where higher rankings indicate better, usually simpler regulations for businesses and stronger protections of property rights.

(differential geometry) A theorem stating that, for an elliptic differential operator on a compact manifold, the analytical index (related to the dimension of the space of solutions) is equal to the topological index (defined in terms of some topological data).

A catalogue of traditional tales based around motifs used in folklore studies.