How to say "mutual" in Japanese

• 同士どうしJLPT N1approx.Common
  noun, noun (suffix)Really denotes fellows, companions or comrades — people of the same kind; its 'mutual' sense amounts to 'each other' among such people, so for mutual respect or understanding it is seldom the word you want.
  １０代だいの友ともだち同士どうしが徹夜てつやでおしゃべりした。↗

  The teenage friends stayed up talking all night.
• 共通きょうつうJLPT N3approx.Common
  no-adjective, na-adjectiveCovers 'mutual' as 'shared': something held in common by two or more people, as in mutual interests or a mutual friend; the point is what both parties have alike, not exchange between them.
• 相互そうごJLPT N2approx.Common
  no-adjectiveThe word for 'mutual' as a two-way relation: each party acts toward or receives from the other, as in mutual understanding, respect or dependence; 'reciprocal' is a near-equivalent.
  それは相互そうご理解りかいの欠如けつじょがもとになっていると思おもう。↗

  I think that is based on a lack of mutual understanding.

Use 相互 for a two-way mutual relation or action, 共通 for something two or more people share, and 同士 for fellows or companions — its 'mutual' sense is limited to 'each other' among them.

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

• 同士どうしfellow
• 共通きょうつうcommon
• 相互そうごmutual
• 互恵的ごけいてきreciprocal