1. An increase, especially a small or incremental one: last week's uptick in interest rates.
2. A transaction in a stock market security above the price of the previous transaction.

[From the indication of a rise in price of a stock by a plus sign on boards above stock market stations.]

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.