Examples from the Web for copperhead
I fully expect the same slur to come out in relation to “Copperhead.”
Betty had dreaded its being either a rattler or a copperhead.Betty Lee, Sophomore|David Goodger (email@example.com)
Copperhead at Macleod was fretting his life out like an eagle in a cage.The Patrol of the Sun Dance Trail|Ralph Connor
They could proudly tread on the rattlesnake and copperhead, but never fell before the worm of the still.Select Temperance Tracts|American Tract Society
British Dictionary definitions for copperhead
Word Origin and History for copperhead
Trigonocephalus contortrix, 1775, American English, so called for color markings between its eyes; see copper + head (n.). Poisonous "sneak snakes" (because they bite without warning), the name is said to have been first used in reference to Northerners suspected of Southern sympathies in Greeley's New York "Tribune," July 20, 1861. Charles H. Coleman, "The Use of the Term 'Copperhead' During the Civil War" ["Mississippi Valley Historical Review" 25 (1938), p.263] traces it to an anonymous letter against Ohio anti-war Democrats in the Cincinnati "Commercial" newspaper in the summer of 1861. It seems not to have been in widespread use until summer 1862.