mid-14c., "that is such by its essence," from Late Latin essentialis, from essentia "being, essence," abstract noun formed (to translate Greek ousia "being, essence") from essent-, present participle stem of esse "to be," from PIE root *es- "to be." 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.