[…] it is the principle of extension, as opposed to restriction, of the sphere of meaning of a term. A name won by specialization begins an independent career, which ends in its gaining the position of head of a tribe.
- Whitney (1875), a pag.84

The extension of a name’s application […] involves a great deal […] Not only a true accordance in generic character, but relations of an infinitely looser kind, are used to tie together the classes that go under one name.
- Whitney (1875), a pag.85