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[awr-nuh-theen] /ˈɔr nəˌθin/
noun, Biochemistry.
an amino acid, H 2 N(CH 2) 3 CH(NH 2)COOH, obtained by the hydrolysis of arginine and occurring as an intermediate compound in the urea cycle of mammals.
Origin of ornithine
1880-85; ornith(uric acid), secreted by birds + -ine2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for ornithine


an amino acid produced from arginine by hydrolysis: involved in the formation of urea in the liver; diaminopentanoic acid. Formula: NH2(CH2)3CHNH2COOH
Word Origin
C19: from ornithuric (acid) secreted in the urine of birds, from ornitho- + uric
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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ornithine in Medicine

ornithine or·ni·thine (ôr'nə-thēn')

Abbr. Orn An amino acid formed by the hydrolysis of arginine and important in the formation of urea.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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ornithine in Science
An amino acid not found in proteins, formed by hydrolyzing arginine and important in the formation of urea. Chemical formula: C5H12N2O2.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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