ETYMOLOGY
from Middle English thornhog, equivalent to thorn + hog
(hog was also used for hedgehog, aardvark, capybara)
EXAMPLE
“… zuyche men byeþ anlykned to þe þorn-hog. þet ys al ywryȝe myd prikyinde eles. and hit is to moche fel..”
From: Dan Michel’s Ayenbite of Inwyt : or, Remorse of Conscience, 1340
Lexicophilia 