adjective

chivalrous, courteous, or honourable.

his gentlemanly behaviour

chivalrous,gallant,honourable,noble,courtly,courteous,civil,respectful,polite,well mannered,well bred,well behaved,attentive,gracious,considerate,thoughtful,obliging,accommodating,cultivated,cultured,civilized,polished,refined,suave,urbane,mannerly,gentle