Plain English Meaning
A tiny tube that lets air move between your middle ear and your throat so the pressure on both sides of your eardrum stays balanced.
Full Definition
A small passage connecting the middle ear to the back of the throat, which opens periodically to equalize air pressure between the middle ear and the surrounding atmosphere.
Context Anchor
Seen in aviation physiology discussions about the ears, especially when learning why climbs and descents can cause ear pressure or pain.
Derivation
Named after Bartolomeo Eustachi, a 16th-century Italian anatomist who described it. Knowing it is a name (not a technical word) removes the temptation to look for a hidden meaning in 'Eustachian.'