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

But Mari is also imbued with a deep self-confidence and appears largely unfazed by the seismic task of dealing with the most demanding woman in fashion. —Alex Ritman, Variety, 1 May 2026

The ruling sharply curtailed lawmakers’ ability to use race as a consideration when drawing voting maps, a seismic decision that is likely to kick off a wave of heated redistricting battles across the country. —Kacen Bayless, Kansas City Star, 29 Apr. 2026

The team studied seismic reflection data -- essentially an ultrasound of the shallow subsurface of the upper 6 miles of the Earth's crust -- to form acoustic waves that travel through the sediments and create an image of the subsurface. —Julia Jacobo, ABC News, 29 Apr. 2026

Johnson, a champion with the Hurricanes and in Dallas bringing the Shula era to an end was seismic change. —Greg Cote april 28, Miami Herald, 28 Apr. 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)