What does .C stand for?

What does .C mean?

C	Convergent Academic & Science » Mathematics
C	Complex Academic & Science » Mathematics
C	Coefficient Academic & Science » Mathematics
C	Circle Academic & Science » Mathematics
C	Roman numeral 100 Academic & Science » Mathematics
C	Cosmopolitan Community » Media
C	Cable Community » Media
C	Context Community » Media
C	Concise Community » Media
C	Civilization Community » Media
C	Controversial Community » Media
C	Clarification Community » Media
C	Cited Community » Media
C	Character Community » Media
C	Classic Community » Media
C	Comedy Community » Media
C	Circular Community » Media
C	Cover Community » Media
C	Centigrade Academic & Science » Meteorology
C	Cool Academic & Science » Meteorology
C	Calm (no wind) Academic & Science » Meteorology
C	Cloud Academic & Science » Meteorology
C	Conditions Academic & Science » Meteorology
C	Celsius Academic & Science » Meteorology
C	Combat Governmental » Military