(grammar) A form of a word that refers to only one person or thing.

(logic) That which is not general; a specific determinate instance.

Being only one of a larger population.

Being the only one of the kind; unique.

Distinguished by superiority: peerless, unmatched, eminent, exceptional, extraordinary.

Out of the ordinary; curious.

(grammar) Referring to only one thing or person.

(linear algebra, of matrix) Having no inverse.

(linear algebra, of transformation) Having the property that the matrix of coefficients of the new variables has a determinant equal to zero.

(set theory, of a cardinal number) Not equal to its own cofinality.

(law) Each; individual.