by mistake

Prepositional phrase

idiomatic

(idiomatic) by accident; without intention to do so

Japanese Meaning

誤って / 意図せずに / うっかり

I deleted the wrong file by mistake while trying to clean up my desktop.

デスクトップを整理しようとして、うっかり間違ったファイルを削除してしまいました。

Sense（1）

(idiomatic) by accident; without intention to do so

Today I took your packed lunch to work by mistake.