imitative of the sound of a dog's barking, 1570s. Compare Latin baubor, Greek bauzein "to bark," etc., and see bay (n.3).
Entries linking to bow-wow
bay n.3
"deep-toned howl of a dog," early 14c., earlier "howling chorus raised (by hounds) when in contact with the hunted animal," c. 1300, from Old French bayer, from PIE root *bai- echoic of howling. Compare Greek bauzein, Latin baubari "to bark," Lithuanian baubti "cry," of cows, etc.; English bow-wow; also see bawl.
From the condition of a hunted animal comes the transferred sense of "final encounter," and thence, on the notion of turning to face the danger when further flight or escape is impossible, at bay.