Unellisse

Unellisse is an obscure term that appears in a small number of Italian-language texts but is not part of standard mathematical vocabulary. It is not listed in major Italian dictionaries, and most scholars treat it as a nonstandard coinage or a typographical variant of ellisse, the Italian word for ellipse.

Usage and meanings: Because there is no formal definition, meanings vary by author. In the limited attestations, unellisse is used either as a nonce word to refer to an ellipse in contexts where the writer intends ellisse, or as a mistaken form introduced by typographical errors or dialect influence. There is no consensus on a precise geometric or linguistic definition, and the term does not appear in authoritative treatments of conic sections.

Origin and history: The origin remains unclear. The scarce occurrences suggest it may stem from mis-spelling, editorial oversight, or rare dialectical usage. No widely accepted etymology or historical development is documented.

Relation to ellisse: The standard nomenclature for the ellipse is ellisse (or ellipse in English). When unellisse is encountered in serious writing, editors and readers typically substitute ellisse or ellipse. The practical meaning attributed to unellisse, where it occurs, is effectively the same as that of an ellipse.

See also: Ellipse, Elliptic curve, Conic section.