The word singular may refer to one of several concepts.

• The singular is a grammatical number denoting a unit quantity (as opposed to the plural and other forms)
• A singular matrix is one that is not invertible.
• A measure (mathematics) or probability distribution is called singular if its support has zero Lebesgue measure. More generally, one may speak of an object "singular with respect to a measure μ", and that means that μ replaces the Lebesgue measure above.
• An infinite cardinal number is called singular if it is not a regular cardinal

Also, Number, in linguistics, is a grammatical category used to express the quantity of objects referred to by a noun. ... Look up Plural on Wiktionary, the free dictionary Plural is a grammatical number, typically referring to more than one of the referent in the real world. ... In mathematics, a matrix (plural matrices) is a rectangular table of numbers or, more generally, of elements of a ring-like algebraic structure. ... In mathematics and especially linear algebra, an n-by-n matrix A is called invertible, non-singular or regular if there exists another n-by-n matrix B such that AB = BA = In, where In denotes the n-by-n identity matrix and the multiplication used is ordinary matrix multiplication. ... In mathematics, a measure is a function that assigns a number, e. ... In mathematics, a probability distribution assigns to every interval of the real numbers a probability, so that the probability axioms are satisfied. ... The word support has several specialized meanings: In mathematics, see support (mathematics). ... In mathematics, the Lebesgue measure is the standard way of assigning a volume to subsets of Euclidean space. ... In linguistics, cardinal numbers is the name given to number words that are used for quantity (one, two, three), as opposed to ordinal numbers, words that are used for order (first, second, third). ... An infinite cardinal number κ is called regular if cf(κ) = κ, where cf is the cofinality operation. ...

• In common English, singular means 'unique'.
• SINGULAR is a computer algebra system.
• A mathematical singularity is an object in mathematics. There is also a corresponding physical notion of a gravitational singularity and, more loosely, a technological singularity.