IPA: /ˈrɪmˌrɒk/
KK: /ˈrɪmˌrɑk/
A type of hard rock that forms a steep edge or cliff, usually found at the edge of a plateau or gravel deposit.
The hikers admired the stunning view from the rimrock overlooking the valley.
Rimrock is formed from "rim" (from Old English "rym", meaning edge or border) and "rock" (from Old English "rocc", meaning a large stone or boulder). The word "rimrock" refers to a rock formation that forms the edge or border of a cliff or elevated area.
Think of the 'edge' ('rim') of a 'large stone' ('rock') — that's what rimrock means, a rocky edge.