make a counterattack and return like for like, especially evil for evil; "The Empire strikes back"; "The Giants struck back and won the opener"; "The Israeli army retaliated for the Hamas bombing"
accept (someone) to be what is claimed or accept his power and authority; "The Crown Prince was acknowledged as the true heir to the throne"; "We do not recognize your gods"
accept as legally binding and valid; "acknowledge the deed"
express obligation, thanks, or gratitude for; "We must acknowledge the kindness she showed towards us"
report the receipt of; "The program committee acknowledged the submission of the authors of the paper"