From Greek 'Mentor,' Odysseus's friend who guided his son — the name probably from PIE *men- (to think).
An experienced and trusted adviser who guides a less experienced person, especially in professional or intellectual development.
From Greek 'Méntōr' (Μέντωρ), the name of Odysseus's trusted friend in Homer's Odyssey. When Odysseus left for the Trojan War, he entrusted his household and the education of his son Telemachus to Mentor. The goddess Athena frequently disguised herself as Mentor to counsel Telemachus. The word became common as a generic term for 'wise adviser' after Fénelon's 1699 French novel 'Les Aventures de Télémaque,' where the Mentor character played
It was not Homer but the French bishop Fénelon who turned 'Mentor' into a common noun. His 1699 novel 'Les Aventures de Télémaque' — written to instruct the young Duke of Burgundy — made the Mentor character such a famous symbol of wise guidance that within decades the word had crossed into English and several other European languages as a generic term.