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.
Words nearby ugly as sin
ugh,
ugli,
uglify,
ugly,
ugly american,
ugly as sin,
ugly customer,
ugly duckling,
ugrian,
ugric,
ugsome