Also from investopedia. When gaps are filled within the same...

Also from investopedia.

When gaps are filled within the same trading day on which they occur, this is referred to as fading. For example, let's say a company announces great earnings per share for this quarter and it gaps up at open (meaning it opened significantly higher than its previous close). Now let's say, as the day progresses, people realize the cash flow statement shows some weaknesses, so they start selling. Eventually, the price hits yesterday's close, and the gap is filled.