How to say "agreed" in Japanese

• 一決いっけつ
  noun, suru verb, intransitive verbCovers 'agreed' in the sense of 'settled': a matter has been concluded and decided. A less common word, and seldom the one you want for plain agreement — it reports a settled outcome.
• 了承済みりょうしょうずみ
  no-adjectiveCovers 'agreed' as 'acknowledged and accepted': a proposal or request has been taken in and consented to, with the acceptance already complete. Typical of business communication; a less common word.
  明日あす会合かいごうがあるということは了承りょうしょう済ずみだ。↗

  It is accepted that we'll have a meeting tomorrow.
• 委細承知いさいしょうち
  expression, noun, suru verbCovers 'agreed' through 'understood': the whole situation, details included, has been grasped and accepted. As a reply it amounts to 'understood, and agreed' — a less common phrase.
• 約束されたやくそくされた
  expression, prenominal modifierCovers 'agreed' as 'promised' or 'arranged': something made definite in advance by mutual promise. It characterizes a plan or arrangement as agreed rather than reporting agreement; a less common choice.

All four are less common; choose by sense: 一決 for a matter settled or decided, 「了承済み」 for acceptance already given, 委細承知 for the whole situation understood and accepted, 「約束された」 for something promised or arranged.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 一決いっけつagreed
• 了承済みりょうしょうずみacknowledged
• 委細承知いさいしょうちtotal situation fully understood
• 約束されたやくそくされたpromised