tug 
(tŭg)
(tŭg)v. tugged, tug·ging, tugs
v.tr.
1. To pull at vigorously or repeatedly: tugged the bell rope. See Synonyms at pull.
2. To move by pulling with great effort or exertion; drag: tugged the mattress onto the porch.
3. To tow by tugboat.
v.intr.
To pull something vigorously or repeatedly: tugged at the coat's zipper.
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.
[Middle English tuggen, from Old English tēon; see deuk- in the Appendix of Indo-European roots.]
tugger n.