Definition of earth-shaker in US English:

earth-shaker

noun

Mythology
  • With the. (A name for) Poseidon or Neptune, the god of earthquakes.

Origin

Late 16th century; earliest use found in Abraham Fleming (c1552–1607), author, literary editor, and Church of England clergyman. From earth + shaker, after various Latin and Greek epithets of Neptune (Poseidon), e.g. classical Latin Ennosigaeus and its etymon ancient Greek ἐννοσίγαιος, and also ancient Greek ἐνοσίχθων.

Pronunciation

earth-shaker

/ˈəːθˌʃeɪkə/