1. The act or process of setting into operation or motion.
2. A business or an undertaking that has recently begun operation: grew from a tiny start-up to a multimillion-dollar corporation.

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.