Chinese Characters

Etymology:
Elements  ----  person 人 + mound 阝. Phonetic series - 队.

Simplified from: 隊

In Oracle Bone Characters it was a pictogram of a person 人 upside down (later changed to a pig 㒸 sui to indicate the sound) falling from a mountain 阝. Original mean was fall down. Later borrowed to row, as people walk in a row to avoid fall down from a mountain. It recovers its original meaning adding earth 土 in 坠 zhuì fall.
From a row of people > team, group > and later team, contingent of soldiers

Main Words:

① a row of people; line.

排队 páiduì stand in line; queue up.
插队 chāduì jump a queue.

② team; group.

领队  lǐngduì   lead a group; leader of a group/team
团队  tuánduì  team

③ team; contingent of soldiers.

部队 bùduì  army; troops
队伍  duìwu  troops; army; ranks; contingent; team.
军队  jūnduì armed forces; army; troops.

Discussion and sources

This explanation follows mostly Wang Xiangzhi work. Not all Oracle Bone dictionaries include the pictogram for dui, but at least Wang Dapeng et al and Ma Rusen do.

• Ma Rusen (马如森). Dictionary of the Oracle Bone characters used in Yinxu (殷墟甲骨文实用字典). Shanghai University Press. Shanghai. 2008.
  
• Wang Dapeng y Shao Li (王大鹏—邵莉). Dictionary of the most common Oracle Bone characters (甲骨文常用字集字字典). Shanghai University Press. Shanghai. 2012.
  
• Wang Xiangzhi (王祥之). To explain with images the origin of Chinese characters (图解汉字起源). Peking University Press. Beijing. 2009