1. The doctrine that the function of an object should determine its design and materials.
2. A doctrine stressing purpose, practicality, and utility.
3. Philosophy. The doctrine in the philosophy of mind according to which mental states are defined by their causes and effects.

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.