tu·tor 
(ttər, ty-)
(ttər, ty-)n.
1.
a. A private instructor.
b. One that gives additional, special, or remedial instruction.
2. A teacher or teaching assistant in some universities and colleges having a rank lower than that of an instructor.
3. A graduate, usually a fellow, responsible for the supervision of an undergraduate at some British universities.
4. Law The guardian of a minor.
v. tu·tored, tu·tor·ing, tu·tors
v.tr.
1. To act as a tutor to; instruct or teach privately.
2. To have the guardianship, tutelage, or care of.
v.intr.
1. To function as a tutor.
2. To be instructed by a tutor; study under a tutor.
[Middle English tutour, from Old French, from Latin tūtor, from tūtus, variant past participle of tuērī, to guard.]