1. One that adapts, such as a device used to effect operative compatibility between different parts of one or more pieces of apparatus.
2. Computer Science. A hardware device, such as a printed circuit board, that enables a personal computer to use additional peripheral devices or hardware.

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.