How to say "cooperate" in Japanese

• 助け合うたすけあうCommon
  godan verb, intransitive verbCovers the sense of cooperating as mutual help between people: each side assists the other. Typical of neighbors, family, or classmates supporting one another in daily life.
  女の子おんなのこ達たちはみんなお互たがいに助け合たすけあった。↗

  All the girls helped each other.
• 力を合わせるちからをあわせる
  expression, ichidan verbCovers cooperating in the sense of joining forces: people combine their strength or effort toward one common aim, such as a team or community working together on a project.
  すべての将兵しょうへいが力ちからを合あわせて反撃はんげきした。↗

  All the officers and men joined their efforts against the attack.

Use 「助け合う」 for people helping each other in everyday mutual support, and 「力を合わせる」 when the emphasis is on pooling effort to achieve a shared goal or task.

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

• 助け合うたすけあうto help each other
• 力を合わせるちからをあわせるto join forces
• 手を取り合うてをとりあうto join forces