Operameters

1 clue
Counting devices
Similar answers:
Aattheopera
Aerometers
Altimeters
Ammeters
Anemometers
Anightattheopera
Anitattheopera
Applausemeters
Aquometers
Atandtoperators
Attheopera
Barkingmeters
Barometers
Bathsoapopera
Batteryoperated
Bigtimeoperator
Bigtimeoperators
Binaryoperation
Biniopera
Boostingoperation