%C3 is the Url Encoded version of the A tilde (Ã)

C-3, a United States military designation for the Ford Trimotor

In town and country planning in the UK, C3 is the code for permission to use specific land or premises for dwellings

VIA C3, a computer processor

ISO 216 C3, a standard paper size

Citroën C3, a car

USS Baltimore (C-3), a protected cruiser of the United States Navy

Y-DNA Haplogroup C3

Independent Carrier, (IATA airline designator C3)

plastic explosive C3

Albatros C.III

Chrysler Comprehensive Compensation System, important in the development of Extreme Programming

C3 (complement), a component of the blood clotting control system

Command, control, and communications (C³), a military concept

Tippmann C-3, a Pump-Action Paintball marker that uses propane gas

USS C-3 (SS-14), a United States C class submarine

AEG C.III

Cubed³, a British video game website

tricarbon C₃, a molecule found in interstellar space

C3 (congress), short for Chaos Communication Congress, the biggest annual hacker event in Europe

C-3 Martin, a U.S. military transport aircraft

C3 carbon fixation in plants

Creatures 3 a video game

High C in music (c3 in European notation)

Low C in music (C3 in American notation)

C3 linearization, a computer science algorithm

HMS C3, a British C class submarine

Characteristic energy (C₃) in astrodynamics, equal to the square of the hyperbolic excess velocity

Clinical Cell Culture, a medical technology company

In football, C3 refers to the UEFA Cup

Chevrolet Corvette C3, the third production design of the Chevrolet Corvette

Third cervical vertebra of the vertebral column, in human anatomy