river-bottom

The compound "river-bottom" is a transparent English formation, directly combining two native Old English elements to describe a physical location. The first element, "river," evolved from Old English terms for a flowing stream, ultimately tracing back to the Proto-Indo-European root rei- "to run, flow." The second element, "bottom," meaning the lowest part or foundation, descends from Old English botm, which has cognates across Germanic languages and a probable Proto-Indo-European origin relating to the base of something. The logic of the compound is purely descriptive, literally meaning "the bottom of a river," and its meaning has remained concrete, referring to the bed or ground beneath a river's water.

Structure: river (watercourse) + bottom (lowest part) - river: From Old English riþera, riþre, possibly related to rīþ "stream, flow". Its functional role is to denote the specific type of water body. - bottom: From Old English botm "ground, soil, lowest part". Its functional role is to denote the foundational or deepest part of something.