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.
• In Sura 112 of the Qur'an, Allah is named Singular (according to some translations).

Also,

• 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.