自己

1. Origins, structure, and basic meaning

• Structure: 自己 (じこ) is a formal word for the self and also forms the first element of many compounds.
• Basic usage: One should not decide an accident's cause from personal judgment alone; a training session begins discussion after self-introductions.

2. Common pitfalls and similar expressions

• Self as possessor of judgment and self as part of a compound
  • In 自己の判断, 自己 identifies the judging person, while 自己紹介 is the compound “self-introduction.” Its kanji distinguish it from a homophone meaning accident.