From Longman Business Dictionary
mentormen·tor /ˈmentɔː-tɔːr/ noun [countableC]HUMAN RESOURCES an experienced person who gives advice to less experienced people to help them in their workHe now runs his own company and is a mentor to other young entrepreneurs.
—mentoring noun [uncountableU]She believes that companies should create programs to encourage mentoring and career development.
—mentor verb [transitiveT]Only one of the four trainees she mentored last year has found a permanent post.