Definition of "essential" []

• Constituting or being part of the essence of something; inherent. (adjective)
• Basic or indispensable; necessary: essential ingredients. See Synonyms at indispensable. (adjective)
• Medicine Of, relating to, or being a dysfunctional condition or a disease whose cause is unknown: essential hypertension. (adjective)
• 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. (adjective)
• Something fundamental. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "All the special interest mistresses are there - from Miss December the homemaker to Miss July, who gives a whole new meaning to the term essential oil."
• "Although in strictly speaking, the term essential oil is in reference to the aromatic value of the oils alone."
• "Those groups, he said, require what they call "essential" patents to be licensed on a fair and reasonable basis—which weakens their potency because holders of such patents can't ask for injunctions that would stop use of their technology altogether."