"encrustation on rocks deposited by precipitation from mineral water," at springs, etc., 1780, from German Sinter, which is cognate with English cinder. Related: Sintered; sintering.
1773 (as St. A Claus, in "New York Gazette"), American English, in reference to the customs of the old Dutch colony of New York, from dialectal Dutch Sante Klaas, from Middle Dutch Sinter Niklaas "Saint Nicholas," bishop of Asia Minor who became a patron saint for children. Now a worldwide phenomenon (Japanese santakurosu). Father Christmas is attested from 1650s.
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.