Definition of "allotropy" []

• The existence, especially in the solid state, of two or more crystalline or molecular structural forms of an element. (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.

• "The phenomenon of allotropy is exhibited when an element exists in two or more distinct forms."
• "When it then became a question of forming an opinion of the reason for these different states, several people, e.g. the American scientist Lea, had recourse to the concept of allotropy which existed previously in chemistry, and was illustrated by the typical example of phosphorus with its two so-called allotropic modifications, the yellow and the red."
• "About a fourth of the hold was similarly constructed, in order to bring back minerals whose allotropy required Jovian surface conditions."