adenine By Ivan Suarez Robles 13 Nov, 2010 One of the four nitrogenous bases found in DNA; pairs with the base thymine. Often abbreviated as the letter “A”. Also found in RNA, where it pairs with the base uracil.Related Articles: Glossary: FADNPR's This American LifeGlossary: thymineGlossary: uracilAll About Mutations