IPA: /ˈkɔːrtliɪst/
KK: /ˈkɔrtliɪst/
The most polite and respectful in behavior or manner, often associated with formal or noble conduct.
He was known for his courtliest manners at the royal banquet.
Courtliest → It is formed from "courtly" (from Old French *cortois*, meaning polite or refined) and the superlative suffix "-est" (meaning most). The word "courtliest" means most polite or refined, as if one were behaving in a manner befitting a royal court.
Think of someone being the "most refined" or "most polite" in a royal setting, which helps you remember that "courtliest" refers to the highest level of politeness.
No commonly confused words.