How to say "countless" in Japanese

• 無数むすうJLPT N2approx.Common
  no-adjective, na-adjectiveCovers 'countless' or 'innumerable' as a direct modifier or predicate. Concise and slightly formal-feeling, it suits descriptions of vast numbers, such as countless stars in the night sky.
  顧かえりみられぬ無数むすうの漂流ひょうりゅう者しゃが家いえを求もとめてる。↗

  A hundred billion castaways are looking for a home.
• 数え切れないかぞえきれないCommon
  i-adjectiveAlso means 'countless', with the nuance that the number is too large to finish counting. Natural when emphasizing that tallying is impossible, such as countless memories or countless times.
  空そらには数え切かぞえきれないほど星ほしが出でている。↗

  There are more stars in the sky than I can count.

Both words mean 'countless': 無数 is the compact noun-like term, while 「数え切れない」 is a longer expression emphasizing that things cannot be counted to the end; either is usually acceptable.

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

• 無数むすうinnumerable
• 数え切れないかぞえきれないcountless
• 数知れないかずしれないcountless
• 数知れぬかずしれぬcountless
• 数知れずかずしれずcountless
• 腐るほどくさるほどmore than one can possibly use