earthquake

Earthquake comes from Middle English erthequake, a straightforward joining of erthe (earth) and quake, itself from Old English cwacian, meaning to shake. The compound simply names the thing it describes: the earth shaking.

The word replaced an older Middle English term, eorð byfung, which came from Old English eorþbeofung, literally 'earth shaking' — so English swapped one shaking-word for another rather than changing the meaning.

Quake traces back to Old English cwacian, from Proto-Germanic *kwakōną, linking earthquake to any English word built on that same root of trembling.