1. Begotten and born out of lawful matrimony; illegitimate. See bastard, note.
2. Lacking in genuineness; spurious; false; adulterate; applied to things which resemble those which are genuine, but are really not so. That bastard self-love which is so vicious in itself, and productive of so many vices. (Barrow)
3. Of an unusual make or proportion; as, a bastard musket; a bastard culverin.
4. Abbreviated, as the half title in a page preceding the full title page of a book.
(Science: medicine) bastard ashlar, three to five quill feathers on a small joint corresponding to the thumb in some mam malia; the alula.