An Etymological Dictionary of the German Language/Bastard
Bastard, m., ‘bastard,’ from Fr. bâtard, bastard (Ital. bastardo), borrowed in the Middle Ages (MidHG. bastart). MidE. bast, ‘illegal marriage,’ and OFr. fils de bast, ‘illegitimate son,’ indicate the primary meaning of the Rom. word, which came to England with William I., and at a later period made its way to Scandinavia. The OFr. bastard (Fr. bâtard) has a Teut. termination; see Bankert. The first part of the word, which in MidE. and OFr. signifies ‘illegal marriage,’ is generally derived from MidLat. and Rom. bastum, ‘pack-saddle’; comp. Ital. and Span. basto, Fr. bât, ‘pack-saddle.’ Bastard would then mean ‘the son of a pack saddle’ (comp. Bast) the saddles serving the Spanish muleteers as beds; comp. Bankert. Scand. bastarðr, whence some would derive the modern Europ. word, did not reach the North before 1200 A.D. nearly.