Cur
Meaning: A dog of unknown background, but even more significantly, of unpleasant and potentially threatening demeanor.
Origins & History: Said to have originated from around 1220 and to be based on the sound of growling – “Grrr…” The initial recorded version of the word is as a prefix in the medieval English kurdogge (in which the syllable kur – relates to Old Norse kurra, “to growl”). This would make more sense that trying to relate the term to Norman French expressions, from which English has derived such words as occur and recur, in which the element -cur has to do with “running (in a course or on a path).” To the Norman French, dogs were not runners but hunters; it also fits with the fact that English cur might through Old Norse therefore be cognate with Finnish koira, “dog.”
*From the book Dog the Wag by Mike Darton
