noun
former teacher; old teacher
Refers to a teacher one had in the past, often with a sense of respect or nostalgia. Not used for a teacher who is simply old in age.
先日、旧師を訪ねて近況を報告した。
The other day I visited my former teacher and gave an update on how I've been.
旧師の教えは今でも私の心に残っている。
My old teacher's lessons still remain in my heart.