rock fan1
/ˌrɒk ˈfan/Geomorphology
noun
A convex, fan-shaped rock surface, typically covered with rock fragments, formed by water erosion, typically at the foot of a slope where the course of a stream widens and becomes less steep.
Origin
Early 20th century. From rock + fan.
rock fan2
/ˈrɒk fan/noun
An enthusiast of rock music.
Origin
1950s; earliest use found in The Guardian. From rock + fan.