lifeline

(noun) a crease on the palm; its length is said by palmists to indicate how long you will live. Synonyms: line of life, life line.

(noun) support that enables people to survive or to continue doing something (often by providing an essential connection). Examples: "The airlift provided a lifeline for berlin." "She offered me a lifeline in my time of grief."

(noun) line that raises or lowers a deep-sea diver.

(noun) line thrown from a vessel that people can cling to in order to save themselves from drowning.