lifeline

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An anchored line thrown as a support to someone falling or drowning.
2. n. A line shot to a ship in distress.
3. n. A line used to raise and lower deep-sea divers.
4. n. A means or route by which necessary supplies are transported.
5. n. One that is or is regarded as a source of salvation in a crisis.
6. n. A diagonal line crossing the palm of the hand and believed to indicate the length and major events of one's life.

Century Dictionary and Cyclopedia

1. n. Nautical: A rope stretched anywhere on a vessel for the safety of the men in bad weather or when they are manning yards: in the latter case it is stretched from the mast to the lift.
2. n. One of several lines attached to a life-buoy or life-boat, to enable a person in the water to reach the boat or buoy more readily.
3. n. A line used by firemen to lower people from a burning building.

Wiktionary

1. n. A line to which a drowning or falling victim may cling to.
2. n. A means or route for transporting indispensable supplies.
3. n. A source of salvation in a crisis.
4. n. nautical On the deck of a boat, a line to which one can attach oneself to stay aboard on rough seas

GNU Webster's 1913

1. n. (Naut.) A line attached to a life boat, or to any life saving apparatus, to be grasped by a person in the water.
2. n. The anem given to one of the creases on the palm; its length is said by palmists to indicate how long one will live.
3. n. A line or rope which raises or lowers a deep-sea diver.
4. n. A line from a vessel that people in a body of water can cling to to save themselves from drowning.

WordNet 3.0

1. n. a crease on the palm; its length is said by palmists to indicate how long you will live
2. n. line that raises or lowers a deep-sea diver
3. n. line thrown from a vessel that people can cling to in order to save themselves from drowning
4. n. support that enables people to survive or to continue doing something (often by providing an essential connection)
5. n. a crease on the palm; its length is said by palmists to indicate how long you will live