rain-swollen

The compound adjective 'rain-swollen' is a transparent descriptive formation from two native English elements. 'Rain' originates from the Proto-Germanic regna-, a term for precipitation. 'Swollen' derives from the Old English swellan, meaning 'to grow or make larger', from the Proto-Germanic swellaną. The compound logically combines the cause ('rain') with the visible effect ('swollen'), creating a vivid term primarily used in environmental and meteorological contexts to describe bodies of water expanded by rainfall. Its formation follows a classic Germanic pattern of noun-adjective compounding to efficiently denote a specific condition.

Structure: rain (water from clouds) + swollen (enlarged) rain: Old English regn, of Germanic origin; related to Dutch regen and German Regen. Functions as a noun used attributively to specify the cause. swollen: Past participle of the verb swell, from Old English swellan, of Germanic origin. Functions as an adjective describing the resulting state.