vital

/ˈvī-tᵊl/

Middle English, from Latin vitalis of life, from vita life; akin to Latin vivere to live

adjective

  1. of the utmost importance

  2. fundamentally concerned with or affecting life or living beings: such as

  3. tending to renew or refresh the living : invigorating

a vital clue

essential fundamental vital cardinal mean so important as to be indispensable. essential implies belonging to the very nature of a thing and therefore being incapable of removal without destroying the thing itself or its character. fundamental applies to something that is a foundation without which an entire system or complex whole would collapse.

noun

  1. the breathing capacity of the lungs expressed as the number of cubic inches or cubic centimeters of air that can be forcibly exhaled after a full inspiration

plural noun

  1. signs of life; specifically : the pulse rate, respiratory rate, body temperature, and blood pressure of a person

  2. measurable variables considered to indicate the general state or condition of something

… frightened even more by the fact that a few months ago you were clinically dead—that's right, dead—all vital signs gone.