Definitions of tug:

• noun:   a sudden abrupt pull
• noun:   a powerful small boat designed to pull or push larger ships
• verb:   strive and make an effort to reach a goal

  Example: "She tugged for years to make a decent living"

• verb:   struggle in opposition

  Example: "She tugged and wrestled with her conflicts"

• verb:   pull hard

  Example: "The prisoner tugged at the chains"

• verb:   pull or strain hard at

  Example: "Each oar was tugged by several men"

• verb:   move by pulling hard

  Example: "The horse finally tugged the cart out of the mud"

• verb:   tow (a vessel) with a tug

  Example: "The tugboat tugged the freighter into the harbor"

• verb:   carry with difficulty