仲間

1. Origins, structure, and basic meaning

• Structure: 仲間 (なかま) means companions sharing an activity or goal. 仲間と marks a partner in action; 仲間同士で marks reciprocal relations within the group.
• Basic usage: Plans are made with hiking companions, and colleagues are urged to help one another in difficulty.

2. Common pitfalls and similar expressions

• Companion planning together and mutual aid within a group
  • と joins the speaker with companions; 同士で emphasizes reciprocal action among members of the same group. The second is not a relation with one specified person.