Definition of: essential

(ə·sen′shəl) adjective
1. Of or pertaining to the essence or intrinsic nature of anything; substantial; basal; characteristic.
2. Indispensable, necessary, or highly important, as to success or completeness; absolutely requisite; cardinal.
3. Constituting, containing, or derived from the essence or any distinguishing constituent, as of a plant; constitutive: essential oils.
4. Having real existence; real; actual: distinguished from accidental.
5. Having the appearance or properties of an essence. See synonyms under INHERENT, NECESSARY, RADICAL.
—noun
1. That which is essential or characteristic.
2. A necessary element, organ, or part. See synonyms under NECESSITY. [<LL essentialis <essentia. See ESSENCE]
—es·sen′ti·al′i·ty (-shē·al′ə·tē) noun
—es·sen′tial·ly adverb
—es·sen′tial·ness noun