Swing Low
A candle or bar whose low is lower than both the preceding and the following candle's lows — a local price trough.
A swing low is the mirror of a swing high: a bar flanked on both sides by bars with higher lows. It marks a local trough where selling pressure was absorbed and price turned up. Rising swing lows are the hallmark of an uptrend; falling swing lows define a downtrend.
Swing lows become support once price moves away from them. Traders use the most recent swing low as the logical stop placement for long positions — a close below it invalidates the long thesis.