Resistance
Resistance is a price level where selling has repeatedly emerged strongly enough to halt or reverse an advance.
Price rejected at resistance
Resistance is the mirror of support — a ceiling where rising price has historically met enough supply to stall the rally. It is where rallies tend to pause, and a decisive break above it (a breakout) often signals that buyers have taken control.
A level that was once resistance frequently becomes support after price breaks above it, a behaviour known as a support/resistance flip. Like support, resistance is a zone rather than a precise number.