a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return; "sonar is an acronym for sound navigation ranging"; "asdic is an acronym for antisubmarine detection investigation committee"
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"