tidal wave vs cataclysm

tidal wave and cataclysm both are nouns.

Word	Noun	Adjective	Verb	Adverb
tidal wave	Yes	No	No	No
cataclysm	Yes	No	No	No

As nouns, cataclysm is a hypernym of tidal wave; that is, cataclysm is a word with a broader meaning than tidal wave:

tidal wave: an unusual (and often destructive) rise of water along the seashore caused by a storm or a combination of wind and high tide
cataclysm: an event resulting in great loss and misfortune

Other hypernyms of tidal wave include calamity, catastrophe, disaster, tragedy, moving ridge, wave.

tidal wave (noun)	cataclysm (noun)
a wave resulting from the periodic flow of the tides that is caused by the gravitational attraction of the moon and sun	an event resulting in great loss and misfortune
an unusual (and often destructive) rise of water along the seashore caused by a storm or a combination of wind and high tide	a sudden violent change in the earth's surface
an overwhelming manifestation of some emotion or phenomenon