air cannon (toy)
A toy that shoots a burst of air, often producing a visible smoke ring or a loud pop. Commonly used in science demonstrations and as a novelty item.
The children are playing with an air cannon.
We made an air cannon in science class.
Compound of 空気 (くうき, 'air') and 砲 (ほう, 'cannon'). The term describes a device that fires a burst of air, often as a toy or demonstration tool.