Destruction
Annihilation
noun, する verb, の adjective
If you break and destroy something, that is destruction. That is annihilation.
かいめつ
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
その都市は原爆により壊滅しました。
The city was annihilated by the atomic bomb.