D defs.my
Entry 2 senses Webster, 1913

Lifeblood

/(līf"blŭd`)/ · Life·blood · IPA /ˈlaɪfˌblʌd/
01 n. The blood necessary to life; vital blood.
  1. 1.
    The blood necessary to life; vital blood.
  2. 2.
    Fig.: That which gives strength and energy.
    “Money [is] the lifeblood of the nation.” Swift.