What is Lifeline?

Lifeline definition and meaning on Dictionary terms:
a line, fired across a ship or boat, by means of which a hawser for a breeches buoy may be hauled aboard.
a line or rope for saving life, as one attached to a lifeboat.
any of various lines running above the decks, spars, etc., of a ship or boat to give sailors something to grasp when there is danger of falling or being washed away.
a wire safety rope supported by stanchions along the edge of the deck of a yacht.
the line by which a diver is lowered and raised.
any of several anchored lines used by swimmers for support.

a route or means of transportation or communication for receiving or delivering food, medicine, or assistance: This road is the town’s lifeline and must be kept open despite the snow.
assistance at a critical time.