Bullish Reversal
A bullish reversal is a trend change from bearish to bullish that takes place at the bottom of an established downtrend.
On a price chart, this appears as a new set of higher-lows after a prolonged period of lower-lows. Bullish reversals can take place because of positive developments in the broader economy or good news specifically relating to an asset (fundamentals).
But they can also occur because an asset drops so low that traders start to see it as undervalued.