adjective

in accordance with the highest standards; faultless.

he had impeccable manners

flawless,faultless,unblemished,spotless,stainless,untarnished,perfect,exemplary,ideal,model,virtuous,pure,moral,sinless,upright,irreproachable,unimpeachable,blameless,guiltless,above suspicion,beyond reproach,beyond criticism,incorrupt,uncorrupted,squeaky clean,whiter than white,lily white,as pure as the driven snow