tug

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To pull at vigorously or repeatedly: synonym: pull.
• intransitive verb To move by pulling with great effort or exertion; drag.
• intransitive verb To tow by tugboat.
• intransitive verb To pull something vigorously or repeatedly.
• noun An instance of tugging; a strong or sudden pull.
• noun A pulling force.
• noun A contest; a struggle.
• noun A tugboat.
• noun A land, air, or space vehicle that moves or tows other vehicles.
• noun A rope, chain, or strap used in hauling, especially a harness trace.

from The Century Dictionary.

• To pull or draw with sturdy effort or violent strain; haul with force; pull.
• To tow by means of a steam-tug: as, the vessel had to be tugged into port.
• To pull with great effort; haul; drag.
• To exert one's self; labor; strive; struggle; contend; wrestle.
• noun The act of pulling, dragging, or hauling with effort, exertion, or difficulty.
• noun A supreme effort; the severest strain or struggle; a contest; wrestle; tussle.
• noun A vehicle used in some parts of England for conveying timber or fagots.
• noun A small but powerful steam-vessel, whether screw or paddle, constructed for the purpose of towing other vessels.
• noun A chain, strong rope, or leather strap used as a trace; a trace (of a harness).
• noun In mining, an iron hoop to which a tackle is affixed.
• noun An athletic contest in which a number of persons, generally four on each side and limited to a certain weight, tug at the ends of a rope, each side trying to pull the rope from the other, or to pull the other side over a line marked on the ground between the contestants. Also called ropepull.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb To pull with great effort; to strain in labor.
• intransitive verb To labor; to strive; to struggle.
• transitive verb To pull or draw with great effort; to draw along with continued exertion; to haul along; to tow
• transitive verb obsolete To pull; to pluck.
• noun A pull with the utmost effort, as in the athletic contest called tug of war; a supreme effort.
• noun Prov. Eng. A sort of vehicle, used for conveying timber and heavy articles.
• noun (Naut.) A small, powerful steamboat used to tow vessels; -- called also steam tug, tugboat, and towboat.
• noun A trace, or drawing strap, of a harness.
• noun (Mining.) An iron hook of a hoisting tub, to which a tackle is affixed.
• noun an iron hook or button to which a tug or trace may be attached, as on the shaft of a wagon.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb transitive to pull or drag with great effort
• verb transitive to pull hard repeatedly
• verb transitive to tow by tugboat
• noun a sudden powerful pull
• noun nautical a tugboat
• noun slang An act of masturbation

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb strive and make an effort to reach a goal
• verb pull or strain hard at
• noun a powerful small boat designed to pull or push larger ships
• verb carry with difficulty
• verb struggle in opposition
• verb pull hard
• noun a sudden abrupt pull
• verb move by pulling hard
• verb tow (a vessel) with a tug