This is the 9798th most frequent Japanese word.
裏切る
"裏切る" means "to betray" or "to turn against someone."
The word '裏切る' is used here to mean 'to betray' in the sense of failing to meet expectations or trust.
彼の行動は期待を裏切った。
His actions betrayed expectations.
In this sentence, '裏切る' refers to the act of being disloyal or betraying someone's trust on a personal level.
親友を裏切ることは許されない。
Betraying a close friend is unforgivable.
Here, '裏切る' is used in a passive form to mean 'betrayed,' suggesting an absence of unexpected disappointment or compromise in the plan.