[thahy-meen, -min]
noun Biochemistry.
  1. a pyrimidine base, C5H6N2O2, that is one of the principal components of DNA, in which it is paired with adenine. Symbol: T

Origin of thymine

First recorded in 1890–95; thym(ic)2 + -ine2 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for thymine

Historical Examples of thymine

  • The difference between these two bases is one methyl group: thymine is a 5-methyluracil.

  • Of the four basic components on the right, thymine occurs in the nucleic acid from the thymus gland.

British Dictionary definitions for thymine


  1. a white crystalline pyrimidine base found in DNA. Formula: C 5 H 6 N 2 O 2

Word Origin for thymine

C19: from thymic (see thymus) + -ine ²
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

Word Origin and History for thymine

1894, from thymic (1868, from Greek thyme; see thyme) + chemical suffix -ine (2).

Online Etymology Dictionary, © 2010 Douglas Harper

thymine in Medicine


  1. A pyrimidine base that is an essential constituent of DNA.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

thymine in Science


  1. A pyrimidine base that is a component of DNA. It forms a base pair with adenine. Chemical formula: C5H6N2O2.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.