IPA: //ʌnˈʃɪv.əl.rəs//
KK: /ʌnˈʧɪvəlrəs/
Not showing the qualities of honor, courtesy, or bravery that are traditionally associated with knights.
His unchivalrous behavior during the debate surprised everyone.
Unchivalrous → It is formed from "un-" (meaning not) and "chivalrous" (from Old French *chevalereux*, meaning knightly or gallant). The word "unchivalrous" means not behaving in a knightly or gallant manner, often implying a lack of honor or courtesy.
Think of 'not' ('un-') being added to 'knightly' ('chivalrous') to remember that 'unchivalrous' describes someone who does not act with the honor and courtesy expected of a knight.