means A private teacher who works with one student or a small group, guiding them through a subject at their own pace.

from From Latin 'tutor,' meaning 'guardian' or 'protector,' built on 'tueri,' to watch over or look after. The earliest tutors weren't lesson-givers but legal guardians keeping an eye on the young; the sense narrowed over the centuries to the one who watches over your learning rather than your whole estate.