“I ate a grinder – elsewhere {meaning outside New England} called a hero, hoagie, poorboy, submarine, sub, torpedo, Italian – and drank a chocolate frappe {another New England term}  -- elsewhere called a milkshake or malted. Although the true milkshake doesn’t exist east of the Appalachians, the grinder was the best thing to happen to me in a day: thinly sliced beef and ham, slivered tomatoes, chopped lettuce, and minced hot peppers, all dressed down with vinegar and oil. I went back to the window to order another.’’

-- William Least Moon, in Blue Highways (1982)

The origin of the word “grinder has several possibilities. One theory is that it came from Italian-American slang for dock workers, of whom there were many in southern New England, and among whom the sandwich was popular. Others say that it was called a grinder because the bread's hard crust required much chewing.