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

Trump’s reelection dashed the view that his first presidency was a mere aberration, and his second administration’s early, seismic actions on global trade, skepticism toward allies, and affection for erstwhile adversaries have already changed the United States’ role and image in the world. —Rebecca Lissner, Foreign Affairs, 24 June 2025

There have been seismic technological changes in the film industry before. —ArsTechnica, 24 June 2025

The impact of smartphone witnessing has been immediate and unmistakable – visceral at street level, seismic in statehouses. —Allissa V. Richardson, The Conversation, 18 June 2025

With 120 active volcanoes across the nation, seismic activity remains a persistent threat. —Barney Henderson john Feng, MSNBC Newsweek, 17 June 2025

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)