師 master, teacher

The bureaucrats are the masters of the small city.

teacher ★★☆☆☆ F
教 (teach) + 師 (master, teacher) = 教師 (teacher)

teacher - more fomal than　先生。

doctor ★☆☆☆☆ NP
医 (doctor) + 師 (master, teacher) = 医師 (doctor)

a more formal word for doctor -(you wouldn't say "I need to see the 医師!" - you'd say, "I need to see the 医者（いしゃ）！”）

master craftsman ★☆☆☆☆
師 (master, teacher) + 匠 (artisan) = 師匠 (master craftsman)

master craftsman, who teaches disciples and apprentices. If he's awesome but doesn't have apprentices, you don't use this one.