1.
live ember, kindling fire
A small flame or glowing coal kept alive to start a new fire. Historically important before matches were available.
2.
source of conflict, spark (of trouble)
Something that could trigger a conflict, dispute, or problem. Used figuratively to describe a latent cause of trouble.
Usage
The figurative sense (source of conflict) is more common in modern usage than the literal sense. Often used with verbs like くすぶる (to smolder), 残る (to remain), and なる (to become).
Common collocations
Related Words
Compare:
火元 (origin of a fire)