Having little or no importance; not essential.
Biochemistry Being a substance that is required for normal functioning but does not need to be included in the diet because of the body's ability to synthesize it from other nutrients.
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.