The word was used by Scott in Guy Mannering. The word is derived by John Jamieson from "worry" ("wirry", in its old sense of harassment in both English and Lowland Scots and "to cow/cowe" (i.e. "to frighten") , but as the second element sometimes appeared as "carl", Charles MacKay thought more likely that the second word was a corruption of "carl" (a man or fellow). The first word is possibly akin to "Urisk" (ùruisg, a brownie). The "urisk" was similar in attributes to the "lubber fiend" of Milton, and the wirry-cow itself.
It is noteworthy that "wirry-" appears in several other old compound words.