Definition of "molecule" []

• The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms; a group of like or different atoms held together by chemical forces. (noun)
• A small particle; a tiny bit. (noun)

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.

• "Each protein molecule is made up of several thousand atoms."
• "The labeled protein molecule is transported to a type of waste disposer inside the cell called the proteasome, which recognizes the label rather like a key fitting into a lock."
• "The ubiquitin molecule is transferred to a different enzyme,"