How to say "optimal" in Japanese

• 最適さいてきCommon
  na-adjective, no-adjectiveThe usual word for 'optimal': something that is best or most suitable among the available options. It fits optimal solutions, choices, and conditions in ordinary speech and writing.
  彼かれはこの計画けいかくに最適さいてきである。↗

  He is the best for this project.
• 至適してき
  na-adjectiveA less common word meaning 'optimal' or 'optimum', found chiefly in scientific and technical writing. For general purposes this is seldom the word you want; use 最適 instead.

Use 最適 for the ordinary sense of 'optimal' — the best or most suitable option — in general contexts; reserve 至適 for the technical 'optimum' found mainly in scientific writing.

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

• 最適さいてきmost suitable
• 至適してきoptimal