Wiktionary
captainly
a. Befitting a captain.
Usage examples of "captainly".
Listen, man, for Christ's sake, I am not trying to usurp your captainly prerogatives and I most assuredly don't want to be the next captain myself.
He had never expected such a thing to be part of his captainly responsibilities, and he has no very clear idea of what he is going to say.
She supposed Becker's remark was compounded of embarrassment and the sense of captainly importance he assumed with his fancy uniform.
When he didn’t let me go, I shrugged him off with captainly force and turned to look for Spock.