tug

Concise Oxford English Dictionary © 2008 Oxford University Press:
tug/tʌɡ/

▶verb (tugs, tugging, tugged)

• 1 pull hard or suddenly.

• 2 tow (a ship) with a tugboat.

▶noun

• 1 a hard or sudden pull.

• 2 (also tugboat) a small, powerful boat used for towing larger ships, especially in harbour.

  ■ an aircraft towing a glider.

• 3 a loop from a horse's saddle which supports a shaft or trace.

– derivatives
tugger noun.

– origin ME: from the base of tow1.