1.
understanding, comprehension, consent
Understanding and accepting something; giving one's agreement or acknowledgment.
了解を得る。
To obtain consent.
上司の了解を得てから進める。
I'll proceed after getting my supervisor's approval.
本人の了解なしに写真を使ってはいけない。
You must not use the photo without the person's consent.
関係者全員の了解を得るのに時間がかかった。
It took time to get the consent of all the people involved.
計画を変更する場合は、事前に全員の了解を得なければならない。
If you change the plan, you must obtain everyone's consent in advance.
2.
roger, understood, copy that
An acknowledgment that a message has been received and understood, commonly used in professional/military contexts.
「了解」
"Roger." / "Got it."
「了解です。すぐやります」
"Understood. I'll do it right away."
「明日10時に来てください」「了解です」
"Please come at 10 o'clock tomorrow." "Understood."
了解しました。すぐ対応します。
Understood. I'll handle it right away.
メールで「了解しました」と返事したが、上司には「承知しました」の方がいいと言われた。
I replied "understood" in an email, but my boss told me it's better to use the more formal expression.
承知しました is considered more appropriate when speaking to superiors.
USAGE NOTES:
- 了解 as a response (sense 2) is very common in business and casual contexts.
- Some argue that using 了解 to superiors is inappropriate and that 承知しました is more polite, though this distinction is debated.
COMMON COLLOCATIONS:
- 了解する (to understand, to consent)
- 了解を得る (to obtain consent)
- 了解しました (understood/acknowledged)
- 了解です (understood)
SIMILAR EXPRESSIONS:
- 承知しました - understood (more formal/humble)
- 分かりました - I understand (neutral)
- かしこまりました - certainly (very formal/service industry)