CyoudaoicibaDictYouDict[C 词源字典]
third letter of the alphabet. Alphabetic writing came to Rome via the southern Etruscan "Caeretan" script, in which gamma was written as a crescent. Early Romans made little use of Greek kappa and used gamma for both the "g" and "k" sounds, the latter more frequently, so that the "k" sound came to be seen as the proper one for gamma. To restore a dedicated symbol for the "g" sound, a modified gamma was introduced c. 250 B.C.E. as G. In classical Latin -c- has only the value "k," and thus it passed to Celtic and, via Irish monks, to Anglo-Saxon, where -k- was known but little used.

In Old French, many "k" sounds drifted to "ts" and by 13c., "s," but still were written with a -c-. Thus the 1066 invasion brought to the English language a more vigorous use of -k- and a flood of French and Latin words in which -c- represented "s" (as in cease, ceiling, circle). By 15c. native English words with -s- were being respelled with -c- for "s" (as in ice, mice, lice). In some words from Italian, meanwhile, the -c- has a "ch" sound (a sound evolution in Italian that parallels the Old French one).[C etymology, C origin, 英语词源]