How to say "successful" in Japanese

• 効果的こうかてきCommon
  na-adjectiveCovers 'successful' only in the sense of 'effective': a method, treatment, or measure that works and achieves its aim. For people or ventures that succeed, it is not the word you want.
  その方法ほうほうは粗雑そざつなものであったが、効果的こうかてきだった。↗

  The method was crude, but very effective.
• 盛んさかんJLPT N4approx.Common
  na-adjectiveCovers 'successful' in the sense of 'thriving' or 'prosperous': a business, trade, or activity that is flourishing and doing well. It suggests ongoing vigor and growth rather than a single achieved result.

Use 効果的 when 'successful' means effective — a method or measure that works — and 「盛ん」 when it means thriving or prosperous, of a business or activity that is flourishing.

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

• 効果的こうかてきeffective
• 盛んさかんprosperous
• 実り多いみのりおおいfruitful
• 佳良かりょうgood
• うまいgood (deal, idea, etc.)
• 既遂きすいcommitted (crime; as opposed to attempted)
• まいゆskillful