Numeronym

A numeronym is a word, usually an abbreviation, composed partially or wholly of numerals. The term can be used to describe several different number-based constructs, but it most commonly refers to a contraction in which all letters between the first and last of a word are replaced with the number of omitted letters (for example, "i18n" for "internationalization"). According to Anne H. Soukhanov, editor of the Microsoft Encarta College Dictionary, it originally referred to phonewords – words spelled by the letters of keys of a telephone pad.

A numeronym can also be called an alphanumeric acronym or alphanumeric abbreviation.