Definitions

1. adjective

relating to or resembling a cataclysm, especially a sudden or violent event in the earth’s history.

“The clysmian forces of nature had reshaped the planet’s surface.”

2. noun

a cataclysmic event, especially one caused by a sudden change in the earth’s crust.

“The ancient civilization was devastated by a massive clysmian that had destroyed their city.”