means A teacher or master, especially in martial arts, Japanese language instruction, or any discipline, used as a respectful title for one who guides others.

from From Japanese 先生 (sensei), built from 先 (sen, "before, ahead, prior") and 生 (sei, "born, life") — literally "one born before," the person who came first and therefore knows the way. The characters are read in their Sino-Japanese pronunciation, borrowed long ago from Chinese, where the same compound 先生 (xiānsheng) survives as a polite "mister." The word entered English in the 20th century, riding the spread of judo, karate, and aikido westward.