singulier

Singulier is a French adjective and, in grammar, a noun. As an adjective, it denotes something distinctive, unusual, or exceptional, and can also mean single or solitary when referring to number. It is used to describe people, events, objects, or concepts that stand out from the ordinary, for example a cas singulier (an unusual case) or un esprit singulier (an idiosyncratic mind).

As a noun, singulier refers to the singular form in grammar. In linguistic descriptions, one speaks of le singulier to denote the form used for a single referent, in contrast with le pluriel for the plural form. This usage parallels the English term “singular” when discussing grammatical number.

In mathematics and related disciplines, singulier is the direct French translation of “singular.” This sense appears in terms such as point singulier (singular point of a curve or function), fonction singulière (a function with singularities), and valeur singulière (a singular value). The phrase décomposition en valeurs singulières describes the singular value decomposition (SVD) of a matrix, a fundamental tool in linear algebra. Other uses include la singularité, the concept of a point or circumstance where usual rules fail or become undefined.

Etymology traces singulier to the Latin singulus, meaning one by one or single. In French, it retains nuances of both uniqueness and numerical singledness, and it interacts with related terms such as singulierité (the quality of being singular), pluriel (plural), and généralité in contrast to the particular.