The glow of a river or stream in darkness or dusk, the gleaming surface of a shadowed river (Japanese 川明かり). Kawaakari can refer to the reflection of the moonlight off flowing water, or the gleam of late sun at dusk.
To shadow over and over: to make dark with shadow; to defend: to save or keep from danger. Obumbratus amnis – a river shadowed with trees.
Cooper’s Thesaurus Linguae Romanae & Britannicae, 1578.