Vigintiles

Part of speech: noun

Definitions

1. Having a value of twenty in a numerical system
2. Pertaining to the ordinal position of twenty in a series
3. Relating to anything that is counted as having twenty components or elements

Etymology: "Vigintiles" is the plural of "vigintile", a term for the twentieth part of a distribution, the statistical cousin of the quartile and the percentile. Its root is Latin "viginti", meaning twenty, joined to the adjective-forming suffix "-ile", which English took from Latin "-ilis" to mean "relating to" or "capable of being". The pattern is the same one that gives "decile" (from Latin "decem", ten) and "percentile" (from Latin "per centum", per hundred), so the word follows the same logic as its better-known relatives. The "-ile" ending is what makes these words feel like a family. Splitting a set of values into twenty equal-count groups yields nineteen cut points, and each group is one vigintile. The word is a plain technical coinage built from classical parts, so its story is in the mathematics rather than in any long history of everyday use.