noun
embers; burning remains
Refers to what is left after a fire has mostly died down, such as glowing coals or smoldering pieces.
キャンプファイヤーの燃え残りを水で消した。
We put out the embers of the campfire with water.
残り火 also means embers or remaining fire, but 燃え残り emphasizes the physical pieces left after burning, while 残り火 focuses on the lingering fire or glow.
Compound of 燃え (continuative form of 燃える 'to burn') + 残り (continuative form of 残る 'to remain').