Resounded (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">resounded</span>' is the definition.<br/ ><span class="explanation-format__explanation">('echo' can be a synonym of 'resound')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for echoed that I've seen before include "Rang" , "copied" , "said nothing original" , "Repeated a sound" , "Reverberated; repeated" .)
(Another definition for boomed that I've seen is " Made deep resonant sound - or prospered".)