The word "完了" is formed by combining the character 完, which carries the core meaning of "to finish" or "to be complete", with the character 了, which primarily functions as a grammatical marker indicating a change of state or completed action. Their fusion creates a single unit where the first character provides the substantive meaning and the second intensifies the sense of finality, resulting in a term that conceptually denotes a thorough conclusion, as in "it's over" or "all done".