Groups of notes (6)
I believe the answer is:
chords
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">groups of notes</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for chords that I've seen before include "Groups of notes" , "Combinations of notes sounded together" , "Harmonious blends of notes" , "Combinations of three or more musical notes" , "Combinations of notes in harmony" .)