vital

Etym. online:
"of or manifesting life," from Latin vitalis "of or belonging to life," from vita "life," related to vivere "to live," from PIE root *gweie- (1) "to live" (see bio-). The sense of "necessary or important" is from 1610s, via the notion of "essential to life" (late 15c.). Vital capacity recorded from 1852. Related: Vitally.