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).
2. Fundamentally important or necessary: essential ingredients. See Synonyms at indispensable.
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.
1. Something fundamental.
2. Something necessary or indispensable.
es·sen′ti·ali·ty (-shē-ălĭ-tē), es·sential·ness n.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.