Old English sinder "dross of iron, slag," from Proto-Germanic *sendra- "slag" (source also of Old Saxon sinder "slag, dross," Old Norse sindr, Middle Low German and Middle Dutch sinder, Dutch sintel, Old High German sintar, German Sinter), from PIE root *sendhro- "coagulating fluid" (source also of Old Church Slavonic sedra "cinder").
Initial s- changed to c- under influence of unrelated French cendre "ashes," from Latin cinerem (nominative cinis) "ashes," from or related to Greek konis "dust" (see incinerate). The Latin word was contracted to *cin'rem and the -d- inserted for ease of pronunciation (compare peindre from pingere). The French word also apparently shifted the sense of the English one to "small piece of burnt coal after a fire has gone out" (16c.).
Geological sense "coarse ash thrown out by volcanoes" is from 1774; cinder cone, formed around a volcano by successive eruptions of ash, is recorded from 1849. Related: Cinders.
pseudo-translation of French Cendrillon, from cendre "ashes" (see cinder). Used figuratively for something unappreciated or something that ends at midnight. A widespread Eurasian folk tale, the oldest known version is Chinese (c. 850 C.E.); the English version is based on Perrault's "Cendrillon" (1697), translated from French 1729 by Robert Sambler, but native versions probably existed (such as Scottish "Rashin Coatie").
The German form is Aschenbrödel, literally "scullion," from asche "ash" (see ash (n.1)) + brodeln "bubble up, to brew." Native words, wisely passed over by Sambler, for "woman whose occupation is to rake ciders into heaps" were cinder-woman (17c.); cinder-wench (1712). Used figuratively for "neglected family member" or in reference to something that ends at midnight.