n.1.  An instance of tugging; a strong or sudden pull: gave the leash a tug.
2.  A pulling force: the tug of gravity.
3.  A contest; a struggle: a tug between loyalty and desire.
4. a.  A tugboat.
b.  A land, air, or space vehicle that moves or tows other vehicles: an airplane tug.
 5.  A rope, chain, or strap used in hauling, especially a harness trace.