Rally

A rally is the time when a stock is trending downward but the price point rises for a few days before heading back down. Many people make money trading just pullbacks and rallies but I'd always recommend trading with the stock market and the stock's trend.

Downtrending stocks usually don't head straight down for days at a time - typically the stock will go down for about 5-10 days with a short 3-5 day period where the stock rises before falling back down further than before the rally. If you're looking to get in a short sell swing trade after a rally, make sure of two things (just like in a pullback): first, be sure that the rally does not last any longer than 5 days and secondly, don't trade a stock if during the rally, the price point has risen above resistance. 

If a rally has lasted more than 5 days the general idea is that the stock's downtrend is not as strong as it once was or as strong as it should be. These stocks are not typically good candidates to short sell swing trade.

Additionally, if the rally allowed the stock to go above resistance - this is called a "breakout." Breakouts are not good in any case because it makes the stock a lot less reliable. If it has a few crazy days where it trades out of its norm then you can't trust that its going to perform for you like you plan. Its a rebel - and rebels aren't trustworthy.

The opposite of a rally is a pullback.

Swing-trade-stocks has a great segment on when to get in and when to get out of a trade that helps illustrate pullbacks and rallies.