油断大敵 ゆだんたいてき Meanings Expression don't let your guard down; carelessness is the great enemy; danger comes soonest when it is despised Kanji 油 oil. Read as ユ. 断 sever. Read as ダン. 大 big. Read as タイ. 敵 enemy. Read as テキ. Example sentences 油断大敵。Security is the greatest enemy. Word lists Yojijukugo (四字熟語) Jinuma: Japanese Dictionary · Word lists