Oscillator
An indicator whose values swing within a bounded range and describe where price sits relative to its recent span.
How to read the number
It answers a question about position inside the span of recent intervals, not about the size of the move: the same reading appears on a quiet stretch and on a violent one.
When the metric lies
In a sustained directional move an oscillator pins itself to the edge of its range. An extreme reading there means strength of the move, not its imminent end.
Also known as: momentum oscillator