Simple Definition of seismic
: of, relating to, or caused by an earthquake
: very great or important
Full Definition of seismic
1 : of, subject to, or caused by an earthquake; also : of or relating to an earth vibration caused by something else (as an explosion or the impact of a meteorite)
2 : of or relating to a vibration on a celestial body (as the moon) comparable to a seismic event on earth
3 : having a strong or widespread impact : earthshaking <seismic social changes>
Examples of seismic
Seismic social changes have occurred.
Origin of seismic
Greek seismos shock, earthquake, from seiein to shake; probably akin to Avestan thwaēshō fear
First Known Use: 1858
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