C3

C3 or C-3 can refer to:

C3 (complement), a component of the blood clotting control system
C3 carbon fixation in plants
C-3 Martin, a U.S. military transport aircraft
Tippmann C-3, a Pump-Action Paintball marker that uses propane gas
HMS C3, a British C class submarine
USS C-3 (SS-14), a U.S. C class submarine
USS Baltimore (C-3), a protected cruiser of the U.S. Navy
Characteristic energy (C₃) in astrodynamics
Clinical Cell Culture, a medical technology company
Command, control, and communications, a military concept
High C in music (c3 in European notation)
Low C in music (C3 in American notation)
VIA C3, a computer processor
C3, a standard paper size defined in ISO 216
C3, a form of plastic explosive
Chrysler Comprehensive Compensation System, an originator of software eXtreme Programming
In town and country planning in the UK, C3 is the code for permission to use specific land or premises for dwellings.