Inattentiveness, Let Your Guard Down
noun, verbal noun
If you let someone cut off your oil supply, it's probably because of your inattentiveness. You let your guard down.
ゆだん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
油断大敵ってよく言うよね。
We often say that inattentiveness is the greatest enemy, don't we?
完全に油断してた。
I completely let my guard down.
コウイチには油断をするな。奴は中々手強い男だぞ。
Don’t let your guard down around Koichi. He’s a really tough guy.