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

Nearly six years after Iger’s seismic move – which stunned the media and business worlds and came just prior to the devastation of Covid and when the exec was well shy of his 70th birthday – his motivations to leave remain largely a mystery. —Dade Hayes, Deadline, 3 Feb. 2026

But in terms of the seismic blockbusters that have dominated the last few trade deadlines, don’t hold your breath. —John Hollinger, New York Times, 3 Feb. 2026

Lately, investors seem to be holding something back—amid a barrage of potentially seismic decisions from the White House, markets have barely budged. —Will Gottsegen, The Atlantic, 31 Jan. 2026

Brooks did both, proudly, repeatedly and to seismic effect. —Seth Abramovitch, HollywoodReporter, 30 Jan. 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)