1. Conversion of one substance into another.
2. In many Christian churches, the doctrine holding that the bread and wine of the Eucharist are transformed into the body and blood of Jesus, although their appearances remain the same.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.