A line to which a drowning or falling victim may cling.
(by extension) A source of salvation in a crisis.
A means or route for transporting indispensable supplies.
(engineering) System or structure of vital importance to a community.
(nautical) On the deck of a boat, a line to which one can attach oneself to stay aboard on rough seas.
(underwater diving) A line from the diver to a tender at the surface control point.
(palmistry) A particular crease in the palm.