noun, noun which may take the genitive case particle 'no'
ember; brand; stub (of used candle, match, etc.)
Refers to the remains of something that has been burning: a glowing ember, a charred piece of wood, or the stub of a candle or match after use.
キャンプファイヤーの燃えさしを水で消した。
We put out the embers of the campfire with water.
灰
There were many match stubs in the ashtray.
残り火 specifically means remaining fire or live embers, often with a poetic nuance, whereas 燃えさし is a more concrete term for the physical leftover piece.
Standard kanji-kana mixed spelling; the most common written form.
Alternate kanji spelling using 差し; less common but still encountered.
Rare variant using 止し; may be seen in older texts.
Compound of 燃え (moe, the continuative form of 燃える 'to burn') + さし (sashi, from 差す 'to insert' or 'to remain', here indicating a leftover state). The spelling 燃えさし is the most common representation.