Translation guide
The state or tendency of being unable to remember things. In Japanese, this concept is expressed through nouns describing the trait, adjectives for a forgetful person, and verbs for the act of forgetting. The most common and natural way to describe a forgetful person is using the adjective 忘れっぽい.
Describing someone's general tendency to forget things easily.
An i-adjective meaning 'forgetful' or 'prone to forgetting'. This is the most common and natural way to describe a person who often forgets things.
彼は忘れっぽいから、メモを取ったほうがいい。
He's forgetful, so he should take notes.
最近忘れっぽくなった気がする。
I feel like I've become forgetful lately.
A noun meaning 'forgetfulness' or 'memory lapse'. Often used in the phrase 物忘れが激しい (to be very forgetful).
年を取ると物忘れが激しくなる。
As you get older, forgetfulness becomes more severe.
物忘れが多くて困っている。
I'm troubled by my frequent forgetfulness.
A formal, technical term for 'amnesia' or 'memory loss', often used in medical contexts. Not used in everyday conversation.
健忘症の治療法を研究している。
They are researching treatments for amnesia.
Referring to the action of forgetting something specific.
The basic verb meaning 'to forget'. Use this for specific instances of forgetting.
約束を忘れてしまった。
I forgot the appointment.
彼の名前を忘れた。
I forgot his name.
A formal noun/する-verb meaning 'to forget' or 'slip one's mind'. Often used in business or polite apologies.
A noun/する-verb meaning 'lapse of memory' or 'temporary forgetfulness', often for something you should know well, like a name.
Describing something that has been forgotten or left behind.
A noun meaning 'lost item' or 'something left behind'. Commonly used for personal belongings.
電車に忘れ物をした。
I left something on the train.
忘れ物がないか確認してください。
Please check that you haven't left anything behind.
Passive form meaning 'to be completely forgotten' or 'to fade into oblivion'. Used for things that are no longer remembered.
その事件は人々の記憶から忘れ去られた。
That incident has been forgotten by people.
忘れっぽい is an adjective describing a person's character (forgetful), while 物忘れ is a noun referring to the phenomenon of forgetfulness or memory lapses. Use 忘れっぽい to say someone is forgetful, and 物忘れ to talk about the forgetfulness itself.
彼は忘れっぽい。
He is forgetful.
彼は物忘れがひどい。
He has terrible forgetfulness.
忘却 (ぼうきゃく) is a formal, literary word for 'oblivion' or 'forgetting'. It is not used in everyday conversation about ordinary forgetfulness. Stick to 忘れる or 忘れっぽい for daily use.
その件は失念しておりました。申し訳ございません。
That matter had slipped my mind. I apologize.
His name has slipped my mind and I can't recall it.