adj. 1. Constituting or being part of the nature or essence of something; inherent: "In that era of general good will ... few Americans doubted the essential goodness of their society" (David Halberstam). 3. Medicine Of, relating to, or being a condition or a disease whose cause is unknown: essential hypertension. 4. Biochemistry Being a substance that is required for normal functioning but cannot be synthesized by the body and therefore must be included in the diet: essential amino acids. n. 1. Something fundamental. 2. Something necessary or indispensable. es·sen′ti·ali·ty (-shē-ălĭ-tē), es·sential·ness n. es·sential·ly adv. |
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