vital

The definition of vital is something that is absolutely essential or necessary or a person who is lively and full of life.

(adjective)

See vital in Webster's New World College Dictionary

adjective

of, concerned with, or manifesting life: vital energy
1. necessary or essential to life; being a source or support of life: vital organs
2. affecting, esp. destroying, life; critical, esp. fatal: a vital wound
1. essential to the existence or continuance of something; indispensable: a vital function
2. of crucial importance: a vital matter
affecting the validity, truth, etc. of something: a vital error
full of life and vigor; energetic: a vital personality

Origin: ME < MFr < L vitalis, vital < vita, life, akin to vivere, to live: see bio-

noun

the vital organs, as the heart, brain, lungs, etc.
the essential parts of anything, indispensable for its existence, continuance, etc.

Related Forms:

See vital in American Heritage Dictionary 4

adjective

Of, relating to, or characteristic of life: See Synonyms at living.
Necessary to the continuation of life; life-sustaining: a vital organ; vital nutrients.
Full of life; animated: “The population of the teeming, vital slum . . . declined” (Rick Hampson).
Imparting life or animation; invigorating: the sun's vital rays.
Necessary to continued existence or effectiveness; essential: “Irrigation was vital to early civilization” (William H. McNeill). “A vital component of any democracy is a free labor movement” (Bayard Rustin).
Concerned with or recording data pertinent to lives: vital records.
Biology Used or done on a living cell or tissue: vital dyes; vital staining.
Destructive to life; fatal: a vital injury.