foreshock

UK: /ˈfɔːˌʃɒk/ US: (fôr′shok′, fōr′-)

WordReference Random House Unabridged Dictionary of American English © 2026

fore•shock  (fôr′shok′, fōr′-), n. [Geol.]

1. Geology a relatively small earthquake that precedes a greater one by a few days or weeks and originates at or near the focus of the larger earthquake.

• fore- + shock¹ 1900–05

Collins Concise English Dictionary © HarperCollins Publishers::

foreshock / ˈfɔːˌʃɒk/ noun

1. a relatively small earthquake heralding the arrival of a much larger one. Some large earthquakes are preceded by a series of foreshocks