How to say "solely" in Japanese

• オンリーCommon
  suffixA loanword meaning 'only' or 'solely', used for casual, emphatic focus on one thing. It often follows a noun, as in fan speech singling out one favorite: this person, this one thing, and nothing else.
  なにも田中たなかさんの力ちからがオンリーだというのはない。↗

  This is not to say that Mr. Tanaka did it all on his own.
• もっぱらJLPT N1approx.Common
  adverb, no-adjectiveCovers 'solely' in the sense of exclusivity: something is done wholly or exclusively, to the exclusion of everything else. Typically describes where one's time, energy, or attention is devoted.
  その特権とっけんはもっぱらご婦人ふじんだけに限かぎられている。↗

  The privilege is reserved exclusively for women.
• 一にいつにCommon
  adverbUsed in emphatic assertions like 'it is solely/entirely because of...' to single out one decisive cause or condition. Suits formal statements attributing an outcome entirely to one factor.
• 単にたんにJLPT N3approx.Common
  adverbReally means 'simply' or 'merely': it limits a statement rather than stressing exclusivity. When it glosses 'solely', the nuance is 'just that and nothing more', often softening or downplaying.
  彼かれは単たんに好奇心こうきしんからそれをしただけだ。↗

  He did it simply out of curiosity.
• ひたすらJLPT N1approx.Common
  adverb, na-adjectiveConveys 'solely' as single-minded devotion: pursuing one thing intently, shutting out all else. Fits contexts of earnest, absorbed effort toward a single goal rather than exclusive fact statements.
  彼かれはひたすら成功せいこうを望のぞんで懸命けんめいに働はたらく。↗

  He works hard because he is anxious to succeed.

Choose based on what 'solely' emphasizes: casual emphasis (「オンリー」), exclusivity (「もっぱら」), emphatic assertion (「一に」), mere limitation (「単に」), or devoted single-minded focus (「ひたすら」).

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

• オンリーonly
• もっぱらwholly
• 一にいつにsolely
• 単にたんにsimply
• ひたすらintently
• ひとえにwholly (due to)