lingering evening light; afterglow
Refers to the soft, fading light remaining in the sky after sunset. Poetic and somewhat literary.
山の向こうに夕明りが残っている。
The lingering evening light remains beyond the mountains.
I took a walk while gazing at the afterglow sky.
Compound of 夕 (yū, 'evening') and 明り (akari, 'light'). The reading ゆうあかり is a straightforward combination of the two elements.