"beautiful, fine or graceful in any way," 1877, American English, from pulchritude (from Latin pulchritudo "beauty," genitive pulchritudinis) + -ous. Earlier English had now-obsolete pulcrious "beautiful, fair" (c. 1500).
"beauty, fairness," c. 1400, pulcritude, from Latin pulchritudo "beauty; excellence, attractiveness," from pulcher "beautiful," a word of unknown origin. De Vaan writes that Latin the -ch- spelling is by Greek influence and posits a stem *polkro- or *pelkro-, but that's as far as he confidently takes it.
word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."
<a href="https://www.etymonline.com/word/pulchritudinous">Etymology of pulchritudinous by etymonline</a>
Harper, D. (n.d.). Etymology of pulchritudinous. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/pulchritudinous