hobnail (n.)

"short, thick nail with a large head," 1590s, from nail (n.); the first element probably identical with hob "rounded peg or pin used as a mark or target in games" (1580s), which is of unknown origin. See hob. Because they were used to make heavy boots and shoes, the word was used figuratively for "rustic person" 17c. and after. Related: Hobnailed.