The Collaborative International Dictionary of English v.0.48:
C \C\ (s[=e])
1. C is the third letter of the English alphabet. It is from
the Latin letter C, which in old Latin represented the
sounds of k, and g (in go); its original value being the
latter. In Anglo-Saxon words, or Old English before the
Norman Conquest, it always has the sound of k. The Latin C
was the same letter as the Greek [Gamma], [gamma], and
came from the Greek alphabet. The Greeks got it from the
Ph[oe]nicians. The English name of C is from the Latin
name ce, and was derived, probably, through the French.
Etymologically C is related to g, h, k, q, s (and other
sibilant sounds). Examples of these relations are in L.
acutus, E. acute, ague; E. acrid, eager, vinegar; L.
cornu, E. horn; E. cat, kitten; E. coy, quiet; L. circare,
OF. cerchier, E. search.
Note: See Guide to Pronunciation, [sect][sect] 221-228.
(a) The keynote of the normal or "natural" scale, which
has neither flats nor sharps in its signature; also,
the third note of the relative minor scale of the
(b) C after the clef is the mark of common time, in which
each measure is a semibreve (four fourths or
crotchets); for alla breve time it is written ?.
(c) The "C clef," a modification of the letter C, placed
on any line of the staff, shows that line to be middle
3. As a numeral, C stands for Latin centum or 100, CC for
C spring, a spring in the form of the letter C.