group

1. Origins, structure, and basic meaning

• Structure: 団 is associated with groups or gatherings; its on-reading is だん.
• Basic usage: 集団(しゅうだん) means a group. In contrast, 布団(ふとん) means bedding such as a quilt, and its final part is read とん.

2. Common pitfalls and similar expressions

• Bedding and a group acting together
  • 厚い布団を二枚重ねた means that someone layered two thick quilts. 布団 in this sentence is bedding used as a covering.
  • 学生の集団 refers to a group of students. 集団で行動する means that the group acts together.