essential(redirected from essentiality)
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1. Biochem (of an amino acid or a fatty acid) necessary for the normal growth of an organism but not synthesized by the organism and therefore required in the diet
2. derived from or relating to an extract of a plant, drug, etc.
3. Logic (of a property) guaranteed by the identity of the subject; necessary. Thus, if having the atomic number 79 is an essential property of gold, nothing can be gold unless it has that atomic number
4. Music denoting or relating to a note that belongs to the fundamental harmony of a chord or piece
5. Pathol (of a disease) having no obvious external cause
6. Geology (of a mineral constituent of a rock) necessary for defining the classification of a rock. Its absence alters the rock's name and classification
7. Music an essential note