cur n.

c. 1200, curre, a term, usually depreciatory, for a dog, earlier kurdogge; used of vicious dogs and cowardly dogs, mastiffs and terriers, probably from Old Norse kurra or Middle Low German korren both meaning "to growl" and echoic of a growling dog. Compare Swedish dialectal kurre, Middle Dutch corre "house dog." Meaning "surly, low-bred man" is from 1580s.