vital Look up vital at Dictionary.com
late 14c., "of or manifesting life," from L. vitalis "of or belonging to life," from vita "life," related to vivere "to live," from PIE base *gwei- (cf. O.Pers. *jivaka- "alive;" Gk. bios "life," zoon "animal;" Lith. gyvata "(eternal) life;" O.E. cwic, cwicu "living, alive;" O.Ir. bethu "life;" cf. also bio-). The sense of "necessary or important" is from 1610s, via the notion of "essential to life" (late 15c.).