忘れる
wasureru
Definition
To forget something, or to leave something behind by accident.
Example
鍵を家に忘れてしまった。
Show translation
I accidentally left my keys at home.
Etymology
From classical Japanese 忘る (wasuru), itself rooted in Old Japanese. The kanji 忘 combines 亡 (loss, death) over 心 (heart/mind), vividly suggesting "a heart that has lost something" — i.e., a mind that no longer holds a memory.
Cultural note
Japanese has a rich set of expressions built on 忘れる. For instance, 忘年会 (bōnenkai) — the famous end-of-year party — literally means "a gathering to forget the hardships of the year." The verb also appears in the proverb 喉元過ぎれば熱さを忘れる ("Once past the throat, you forget the heat"), equivalent to the English "out of sight, out of mind."