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"
a representation of a person (especially in the form of sculpture); "the coin bears an effigy of Lincoln"; "the emperor's tomb had his image carved in stone"
a statement acknowledging something or someone; "she must have seen him but she gave no sign of acknowledgment"; "the preface contained an acknowledgment of those who had helped her"