〜忘れる (wasureru) - Forget To
〜忘れる attaches to verb stems to indicate forgetting to do an action. It expresses that an action was supposed to happen but didn't because it was forgotten.
Verb stem + 忘れる
持って行き忘れる - forget to bring
買い忘れる - forget to buy
言い忘れる - forget to say
Action not done
Due to forgetting
Unintentional omission
Formation
Basic pattern
る-verbs:
食べる → 食べ忘れる "forget to eat"
見る → 見忘れる "forget to watch"
閉める → 閉め忘れる "forget to close"
う-verbs:
買う → 買い忘れる "forget to buy"
書く → 書き忘れる "forget to write"
消す → 消し忘れる "forget to turn off"
Irregular:
する → し忘れる "forget to do"
持って来る → 持って来忘れる (awkward, less common)
Core Meaning
Unintentional non-action
宿題をし忘れた
"Forgot to do homework"
Intended to do it
But forgot
Action didn't happen
電気を消し忘れた
"Forgot to turn off the lights"
Should have done it
Slipped mind
Now realizes mistake
Common Contexts
Daily forgetfulness
傘を持って行き忘れた
"Forgot to bring umbrella"
ドアに鍵をかけ忘れた
"Forgot to lock the door"
メールの返事を書き忘れた
"Forgot to write email reply"
Common mistakes
Everyday forgetfulness
Realizing omission
Bringing and taking
持って行き忘れる
"Forget to bring (when going)"
持って帰り忘れる
"Forget to bring back"
持ってくるのを忘れた
"Forgot to bring (when coming)"
Movement + forgetting
Very common pattern
Communication
言い忘れる
"Forget to say/tell"
伝え忘れる
"Forget to convey"
連絡し忘れる
"Forget to contact"
Message not delivered
Communication gap
Tasks and duties
提出し忘れる
"Forget to submit"
予約し忘れる
"Forget to make reservation"
支払い忘れる
"Forget to pay"
Obligations missed
Responsibilities overlooked
Structure Variations
Using の construction
Both patterns possible:
Compound:
買い忘れた "forgot to buy"
の-construction:
買うのを忘れた "forgot to buy"
Compound = more concise
の-construction = more explicit
Both natural and common
Directional Compounds
With movement verbs
持って行き忘れる
"Forget to take (going)"
持って帰り忘れる
"Forget to bring back"
連れて行き忘れる
"Forget to take (someone)"
Complex but natural
Directional meaning preserved
Realizing the Mistake
Common follow-up
あ、忘れた！
"Oh, I forgot!"
宿題をし忘れた！
"I forgot to do homework!"
Often with realization
Sudden awareness
Moment of recognition
Asking if Forgotten
Checking
何か忘れていない？
"Haven't you forgotten something?"
買い忘れたものはない？
"Is there anything you forgot to buy?"
Checking for omissions
Reminding others
Apologizing for Forgetting
Taking responsibility
すみません、言い忘れました
"Sorry, I forgot to tell you"
ごめん、持ってくるの忘れた
"Sorry, forgot to bring it"
Acknowledgment
Apology
Common social situation
With ている
Forgotten state
消し忘れている
"Have forgotten to turn off (still off)"
Current state resulting from forgetting
Action still undone
Ongoing consequence
Negative Forms
Didn't forget
忘れなかった
"Didn't forget"
買い忘れることはなかった
"There was no forgetting to buy"
Successfully remembered
Emphasizing completion
Transitivity
Maintains verb pattern
Transitive verbs:
宿題をし忘れる "forget to do homework"
本を返し忘れる "forget to return book"
Intransitive verbs:
行き忘れる "forget to go"
来忘れる (rare/awkward)
Object patterns preserved
Caution and Reminders
Warnings
忘れないでね
"Don't forget, okay?"
買い忘れないように
"So that you don't forget to buy"
Preventive reminders
Careful warnings
Common Collocations
持って行き忘れる - forget to bring
Very common
買い忘れる - forget to buy
Shopping context
言い忘れる - forget to say
Communication
消し忘れる - forget to turn off
Household
閉め忘れる - forget to close
Doors, windows
These are natural combinations
Learn as phrases
Formality
Neutral usage
Can use in:
- Casual: 忘れた
- Polite: 忘れました
- Written: 忘れた
Adjust with conjugation
Not inherently formal/casual
Conjugation
Regular る-verb
忘れる is a る-verb:
Present: 忘れる
Past: 忘れた
Negative: 忘れない
Te-form: 忘れて
Potential: 忘れられる
Volitional: 忘れよう
Standard conjugations
Double Negative Confusion
"Don't forget to"
忘れないで
"Don't forget"
買うのを忘れないで
"Don't forget to buy"
忘れずに
"Without forgetting"
Negative + forget = remember
Common reminder pattern
Standalone 忘れる
As independent verb
Standalone meaning:
名前を忘れた
"Forgot (someone's) name"
パスワードを忘れた
"Forgot password"
Forgetting information/things
Compound meaning:
買い忘れた
"Forgot to buy"
Forgetting to do action
Different but related uses
Emphasis on Accident
Unintentional nature
Using 忘れる emphasizes:
- Not on purpose
- Accident/mistake
- Didn't mean to omit
- Memory failure
わざと忘れたわけじゃない
"Didn't forget on purpose"
Excuse/explanation
Lack of intention
Prevention Strategies
Reminders
忘れないようにメモする
"Take notes so I don't forget"
忘れないためにアラームをセットした
"Set alarm so I wouldn't forget"
リマインダーを設定する
"Set a reminder"
Proactive measures
Learning from mistakes
In Conditional
"If forget"
もし忘れたら、電話して
"If (you) forget, call me"
買い忘れたら、また行く
"If (I) forget to buy, (I'll) go again"
Contingency planning
Backup plans
Common Mistakes
❌ Using dictionary form
✗ 買う忘れる
✓ Using stem form
✓ 買い忘れる
❌ Confusing with 忘れている
忘れている = have forgotten (state)
忘れる = forget to do (action)
✓ Understand difference in meaning
❌ Wrong particle
✗ 買い忘れるを
✓ Correct structure
✓ 買い忘れる
✓ 買うのを忘れる
Practical Examples
Real-life situations
あ、財布を持って来忘れた！
"Oh, I forgot to bring my wallet!"
ごめん、返事するの忘れてた
"Sorry, I forgot to reply"
窓を閉め忘れて出かけた
"Left without closing the window (forgot to close)"
電気を消し忘れないでね
"Don't forget to turn off the lights, okay?"
傘を持って帰り忘れた
"Forgot to bring back my umbrella"
メールで送るのを忘れた
"Forgot to send (it) by email"
Everyday situations
Common mistakes
Natural contexts
Apologizing and explaining