The Generalization reference article from the English Wikipedia on 24-Jul-2004
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Generalization

Helping orphans the way you would do it
Concept A is a generalization of concept B if and only if: Equivalently, A is a generalization of B if B is a specialization of A.

For instance, 'Animal' is a generalization of 'Bird' because every bird is an animal, and there are animals which are not birds (dogs, for instance).

This kind of generalization versus specialization (or particularization) is reflected in either of the contrasting words of the word pair hypernym and hyponym. A hypernym as a generic stands for a class or group of equally-ranked items, such as tree does for beech and oak; or ship for cruiser and steamer. Whereas a hyponym is one of the items included in the generic, such as lily and daisy are included in flower, and bird and fish in animal. A hypernym is superordinate to a hyponym, and a hyponym is subordinate to hypernym.

See also: inheritance (object-oriented programming), faulty generalization and -onym