■ noun
1》 a rope or line used for life-saving, typically one thrown to rescue someone in difficulties in water or one used by sailors to secure themselves to a boat.
↘a line used by a diver for sending signals to the surface.
2》 a thing on which someone or something depends or which provides a means of escape from a difficult situation.
3》 (in palmistry) a line on the palm of a person's hand, regarded as indicating how long they will live.