essential (adj.) Look up essential at Dictionary.com
mid-14c., "that is such by its essence," from Late Latin essentialis, from essentia (see essence). Meaning "pertaining to essence" is from late 14c., that of "constituting the essence of something" is from 1540s; that of "necessary" is from 1520s. Essentials "indispensable elements" is from early 16c. Related: Essentially.