ember (n.)

"small, live coal," Old English æmerge "ember," merged with or influenced by Old Norse eimyrja, both from Proto-Germanic *aim-uzjon- "ashes" (source also of Middle Low German emere, Old High German eimuria, German Ammern); a compound from *aima- "ashes" (from PIE root *ai- (2) "to burn;" see edifice) + *uzjo- "to burn" (from PIE root *heus- "to burn;" source also of Sanskrit osati "to burn, scorch," usna- "hot;" Greek euo "to singe;" Latin urere "to burn, singe;" Old Norse usli, Old English ysle "hot ashes," Old Norse ysja "fire"). The -b- is unetymological.