"proud and disdainful," 1520s, a redundant 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 had also hautif in this sense (mid-15c., from Old French hautif), and hautein "proud, haughty, arrogant; presumptuous" (c. 1300), from Old French hautain. Related: Haughtily.
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).
<a href="https://www.etymonline.com/word/haughtiness">Etymology of haughtiness by etymonline</a>
Harper, D. (n.d.). Etymology of haughtiness. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/haughtiness