Momentum

What Does Momentum Mean?
The rate of acceleration of a security's price or volume.

Investopedia explains Momentum
Once a momentum trader sees an acceleration in a stock's price, earnings, or revenues, the trader will often take a long or short position in the stock with the hope that its momentum will continue in either an upwards or downwards direction. This strategy relies more on short-term movements in price rather then fundamental particulars of companies, and is not recommended for novices.