noun
harmonium
har-MOH-nee-um/hɑːrˈməʊniəm/
A small keyboard instrument that produces sound by blowing air through reeds.
This wooden harmonium has a keyboard and two foot-operated bellows pedals.

Etymology
The French instrument name was formed from Greek harmonia, “concord of sounds,” literally “means of joining.” It connects the keyboard instrument with musical harmony—the pleasing joining of sounds.
In context
that harmonium is going to be really really really hard to play because it's just going to be running out of air all the time and I'm going to be constantly squeezing trying to get enough air
More examples
- She pumps the harmonium's pedals while playing a slow melody.
- A harmonium accompanies the singers in the small chapel.
- Air passing through reeds gives the harmonium its sound.
Forms
harmonium · harmoniums
Similar words
- reed organ
- Names the broader family of organs using vibrating reeds.
- pump organ
- Emphasizes the foot-pumped bellows that supply the instrument's air.