late 14c., "of or manifesting life," from Latin vitalis "of or belonging to life," from vita "life," related to vivere "to live," from PIE root *gwei- (cf. Old Persian *jivaka- "alive;" Greek bios "life," zoon "animal;" Lithuanian gyvata "(eternal) life;" Old English cwic, cwicu "living, alive;" Old Irish bethu "life;" cf. also bio-). The sense of "necessary or important" is from 1610s, via the notion of "essential to life" (late 15c.). Vital capacity recorded from 1852.
vital vi·tal (vīt'l)
Of, relating to, or characteristic of life.
Necessary to the continuation of life.
Used or done on a living cell or tissue, as in staining.
Destructive to life; fatal, as of an injury.