What does Stochastic Oscillator mean?

The Stochastic Oscillator compares a stock's current closing price to its recent high/low range on a 0-100 scale, similar to RSI.

Stochastic compares the current close to the high/low range over a lookback period, on a 0–100 scale. Like RSI: above 80 is overbought, below 20 is oversold. The %K line crossing the %D line is a common trigger.