Crushing Failure, Utterly Beaten, Overwhelming Defeat
noun, verbal noun
Failure that causes disaster is a crushing failure and you were utterly beaten by your opponent.
ざんぱい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
日本はワールドカップで惨敗してしまった。
Japan suffered a crushing failure at the World Cup.