An Etymological Dictionary of the German Language/Sau
Sau, f., ‘sow, hog,’ from the equiv. MidHG. and OHG. sû, f.; corresponding to AS. sû, E. sow, OIc. sýr, ‘sow.’ Du. zog, zeug, ‘sow,’ belong further, like AS. sŭgu (Goth. *sugus), and Suab., MidLG., and MidE. suge, to OTeut. sû, whence also Schwein (Goth. swein, n.) is derived. The term sû, ‘pig,’ is essentially West Aryan; comp. Lat. sû-s, Gr. ὗ-ς, σῦ-ς, to which Zend hu, ‘boar,’ is allied; for further references see under Schwein. The root is Sans. su, ‘to bring forth’ (comp. Sohn), so that the ‘sow’ was probably named from its fecundity; others regard sû as an imitation of the grunting of the pig, because in Sans. the animal is termed sûkara, lit. ‘sû maker.’ Sau, in its prov. sense, ‘ace’ (of cards), seems, like Hund, to have been an old technical term in dice-playing, yet early references are wanting.