The term "tug" can have multiple meanings depending on its context.
1) In a nautical sense, it refers to a small boat used for maneuvering larger vessels in harbors or docking areas by means of ropes and poles.
2) It may also refer to a strong pull or jerk, as in "giving the tug of war team a hand."
3) In an emotional sense, it can mean to give someone a gentle, affectionate pull on their clothing or hair, often used with children or pets.