(grammar) Pertaining to a language form referring to none of something; compare singular used for one and plural for more than one.

(arithmetic) An empty sum.

(mathematics, of a function) Taking no entries; having trivial domain; having the arity of zero. / (programming, of a function, procedure, command, etc.) Taking no arguments.

plural of nullary sum

An arid karst plain stretching 1142 kilometers in South central Australia just north of the Great Australian Bight.