late 14c., "guardian, custodian," from Old French tuteor "guardian, private teacher" (13c., Modern French tuteur), from Latin tutorem (nominative tutor) "guardian, watcher," from tutus, variant past participle of tueri "watch over, look at," a word of uncertain origin. De Vaan suggests the sense evolution is from "to protect," and suggests connection with Sanskrit tavas- "strong, powerful," Greek sōs "safe, safe and sound, healthy," from a root meaning "to be strong." Specific sense of "senior boy appointed to help a junior in his studies" is recorded from 1680s.