(as) ugly as sin definition
ugly as sin
Physically or morally hideous, as in I can't think why she likes that dog; it's ugly as sin. This simile, first recorded in 1801, replaced the earlier ugly as the devil.
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a children's mummer's parade, as on the Fourth of July, with prizes for the best costumes.|