1550s, from haughty + -ness. Earlier was haughtness (late 15c.).
1520s, an extension of haught (q.v.) "high in one's own estimation" by addition of -y (2) on model of might/mighty, naught/naughty, etc. Middle English also had hautif in this sense (mid-15c., from Old French hautif). Related: Haughtily.