lifeblood

noun

1. (uncountable, usually)Blood that is needed for continued life; blood regarded as the seat of life.

   “[Y]ou desire his mana, yet you respect his tabu, for in you and him alike runs the common life-blood.”

   “You didn't come to me in time. And by the time you came to me that fool of a doctor had bled and leeched the lifeblood out of Timmy.”

   “Beowulf's body was wet with his life-blood: it came welling out.”

   “It was she who stopped the lifeblood flow when Karl misswung an axe until Herta could come.”

2. (figuratively, uncountable, usually)That which is required for continued existence or function.

   “Gasoline is the lifeblood of the modern city.”

   “Information is the lifeblood of the United States and the world.”

   “The road brought invaders who left them hungry and dug up the dead. The road took living children away and made them dead to home. It was as if the roads were veins that bled off lifeblood but never pumped it back in.”

   “'We want to be able to market some of these small stations and the lifeblood lines where we currently have short trains in service.'”

   “Like most Victorian Railways, freight was the line's lifeblood.”