Definitions
1.nounA line to which a drowning or falling victim may cling.
2.noun(by extension) A source of salvation in a crisis.
3.nounA means or route for transporting indispensable supplies.
4.nounSystem or structure of vital importance to a community.
5.nounOn the deck of a boat, a line to which one can attach oneself to stay aboard on rough seas.
6.nounA line from the diver to a tender at the surface control point.
7.nounA particular crease in the palm.