How to say "bilateral" in Japanese

• 二国間にこくかん
  no-adjectiveA kanji term literally meaning 'between two countries'; use it for the diplomatic sense of 'bilateral', as in relations, talks, or agreements between two countries. It is itself a less common equivalent.
  ２国こく間かんの貿易ぼうえき上じょうのアンバランスを改善かいぜんしなければならない。↗

  The trade imbalance between two nations should be improved.
• バイラテラル
  na-adjectiveThe katakana loanword for 'bilateral', covering the same diplomatic sense as 二国間. It is a less common equivalent, so it is seldom the word you need.
• 両国間りょうこくかん
  no-adjectivePrimarily means 'between both countries', referring to two particular countries in the situation at hand. As a rendering of 'bilateral' it is marginal; think of it as describing a specific two-country situation.
  この問題もんだいは両国間りょうこくかんで政治的せいじてき解決かいけつを見みた。↗

  The two countries came to a political settlement over this dispute.

All three are less common equivalents: 二国間 and 「バイラテラル」 both render the diplomatic 'bilateral' (between two countries), the latter as a loanword, while 両国間 means 'between both countries', pointing to two specific countries.

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

• 二国間にこくかんbilateral
• バイラテラルbilateral
• 両国間りょうこくかんbetween both countries