Scissa

Scissa is a term encountered in some mathematical texts as a synonym for abscissa, the x-coordinate of a point in a Cartesian coordinate system. In two- and three-dimensional space, the abscissa (or scissa) of a point determines its position along the x-axis, measured from the origin. It is the signed distance to the yz-plane: positive values indicate positions to the right (positive x) and negative values to the left (negative x). The abscissa is usually paired with the ordinate, the y-coordinate, and, in three dimensions, with the z-coordinate. A point is commonly written as (x, y, z), where x is the abscissa.

Usage and nomenclature vary by language and period. In modern English mathematics, abscissa is the standard term, and scissa appears primarily in older texts or in multilingual contexts. Some languages use variants such as ascissa (Italian), abscisse (French), or abscissa (English-adapting forms). In everyday practice, many educators and textbooks prefer “x-coordinate” to avoid ambiguity, especially for learners new to coordinate geometry.

Relation to other coordinates: the term ordinate refers to the y-coordinate, and the z-coordinate (in three dimensions) is sometimes called the applicate or third coordinate in older literature, though “z-coordinate” is now common. While scissa is not widely used in contemporary English, recognizing it as an historical or alternative form helps in reading older mathematical writings and cross-language sources.