a thing on which someone or something depends or which provides a means of escape from a difficult situation

the telephone has always been a lifeline for Gabby and me

fertility treatment can seem like a lifeline to childless couples

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

he rigged a lifeline fore and aft and clipped the safety line on the girl's life jacket to it

(in palmistry) a line on the palm of a person's hand, regarded as indicating how long they will live