faint light; glimmer; dim light
Refers to a very weak, barely perceptible light, often in darkness or low-light conditions. Used in both literal and slightly literary contexts.
洞窟の奥に微光が見えた。
A faint light was visible deep inside the cave.
月明かりだけが微光を放っていた。
Only the moonlight cast a dim glow.
Compound of 微 (bi, 'faint, minute') and 光 (kō, 'light'). The reading is on'yomi. The word is straightforward and transparent in meaning.