Flat or sharp? (4)
I believe the answer is:
note
I believe this is a double definition.
'flat' is the first definition.
(thesaurus)
'sharp?' is the second definition.
(thesaurus)
(Other definitions for note that I've seen before include "Characteristic" , "Observe - musical symbol" , "Single tone; short letter" , "Short personal letter" , "Short communication" .)