noun
hindsight; wisdom after the fact
Refers to the wisdom or cleverness one has only after an event has passed, often with a nuance of regret or irony. Commonly used in the phrase 後知恵を働かせる (to be wise after the event).
事故が起きてから安全対策を考えるのは後知恵だ。
Thinking about safety measures after an accident has happened is hindsight.
彼はいつも後知恵で物を言う。
He always speaks with the wisdom of hindsight.
Compound of 後 (あと, 'after') and 知恵 (ちえ, 'wisdom'). The reading ぢえ is a rendaku form of ちえ.