Definition of pleistoseist in US English:

pleistoseist

noun

Seismology
  • A line on a map or diagram marking the limit of the area of maximum disturbance in an earthquake; the area itself.

Origin

Late 19th century; earliest use found in James Milne (b. 1865). From German Pleistoseiste from ancient Greek πλεῖστος most + ancient Greek σειστός shaken from ancient Greek σείειν to shake + -τός, suffix forming verbal adjectives.

Pronunciation

pleistoseist

/ˌplʌɪstəˈsiːɪst/