An enumerative definition of a concept or term is a special type of

extensional definition In logic, extensional and intensional definitions are two key ways in which the objects, concepts, or referents a term refers to can be defined. They give meaning or denotation to a term. Intensional definition An intensional definition gives ...

that gives an explicit and exhaustive listing of all the objects that fall under the concept or term in question. Enumerative definitions are only possible for finite sets and only practical for relatively small sets. An example of an enumerative definition for the set ; extant monotreme species (for which the

intensional definition In logic, extensional and intensional definitions are two key ways in which the objects, concepts, or referents a term refers to can be defined. They give meaning or denotation to a term. Intensional definition An intensional definition gives ...

is ''species of currently-living mammals that lay eggs'') would be : platypuses : echidnae: :: short-beaked echidna :: long-beaked echidnae: :::

Sir David's long-beaked echidna Sir David's long-beaked echidna (''Zaglossus attenboroughi''), also known as Attenborough's long-beaked echidna or the Cyclops long-beaked echidna, is one of the three species from the genus ''Zaglossus'' that occurs in New Guinea. It is named i ...

::: eastern long-beaked echidna ::: western long-beaked echidna

See also