seismic

adjective

seis·​mic ˈsīz-mik 

ˈsīs-

1

: of, subject to, or caused by an earthquake

also : of or relating to an earth vibration caused by something else (such as an explosion or the impact of a meteorite)

2

: of or relating to a vibration on a celestial body (such as the moon) comparable to a seismic event on earth

3

: having a strong or widespread impact : earthshaking

seismic social changes

seismically

ˈsīz-mi-k(ə-)lē 

adverb

Examples of seismic in a Sentence

Seismic social changes have occurred.

Recent Examples on the Web

As a part of the $76 million seismic upgrade, crews have begun working on the Broadway Tunnel underneath. — Sooji Nam, CBS News, 17 Aug. 2026

Important issues must be addressed before any decisions are made, including PG&E’s repayment of an existing state loan, seismic and nuclear reactor safety, spent fuel storage and continued revenues to local government and schools, Laird said. — Los Angeles Times, 16 Aug. 2026

The bronze vessel reportedly contained an internal mechanism capable of indicating the direction from which seismic waves had arrived. — Atharva Gosavi, Interesting Engineering, 16 Aug. 2026

An archipelago of more than 17,000 islands, Indonesia is prone to seismic activity and has suffered several devastating earthquakes in the past. — Lex Harvey, CNN Money, 14 Aug. 2026

Word History

Etymology

Greek seismos shock, earthquake, from seiein to shake; probably akin to Avestan thwaēshō fear

First Known Use

1858, in the meaning defined at sense 1

Phrases Containing seismic

• seismic shift

Kids Definition

seismic

adjective

seis·​mic ˈsīz-mik 

ˈsīs-

: of, subject to, or caused by an earthquake or an earth vibration caused by something else (as an explosion)