This is the 8916th most frequent Japanese word.
殲滅
"殲滅" means "annihilation" or "complete destruction."
The word "殲滅" (senmetsu) here is used as a noun indicating the complete annihilation or destruction of the enemy forces.
敵軍を完全に殲滅する作戦が立てられた。
A strategy was planned to completely annihilate the enemy forces.
"殲滅された" (senmetsu sareta) is the past passive form describing that the city was annihilated.
殲滅された都市から生き残りの目撃者が語る恐怖の体験。
Survivors from the annihilated city talk about their terrifying experiences.
"殲滅" (senmetsu) here is used in its nominal form to describe the concept of annihilation as something to prevent.