Fibonacci retracement
/fɪˈbɒnətʃi rɪˈtreɪsmənt/
horizontal lines on a chart at key Fibonacci ratios indicating where support or resistance may occur
“The stock retraced to the 61.8% Fibonacci level before resuming its uptrend.”
Origin: Named after Leonardo Fibonacci (c.1170–1250) whose sequence appears throughout nature and finance