师 is a bound form (b.f.) — it appears as a suffix or root in compounds, not as a standalone word (except for the military sense 'division'). Its core meaning is 'teacher' or 'master', and it extends to indicate a person skilled in a profession (律师 lawyer, 工程师 engineer, 医生 doctor). In Confucian tradition, 师 carries a strong sense of respect for the teacher-student relationship. As a military term, 师 refers to a division, a unit of about 10,000 soldiers.