Main Entry: es·sen·tial

Pronunciation: \i-ˈsen-chəl\

Function: adjective

1 : being, relating to, or containing an essence <an essential odor>
2 : being a substance that is not synthesized by the body in a quantity sufficient for normal health and growth and that must be obtained from the diet <essential fatty acids>—compare nonessential
3 : having no obvious or known cause : idiopathic <essential disease>