Channel 4, a United Kingdom television broadcaster

Churches Covered and Connected in Covenant- Religious Association founded by Archbishop LeRoy Bailey Jr.

C4, an international standard paper size (229*324 mm), defined in ISO 216

Chevrolet Corvette C4, the fourth production design of the Chevrolet Corvette

C4 carbon fixation, a pathway for carbon fixation in photosynthesis

C-4, professional wrestler Paul Burchill's name for his finishing move, a moonsault uranage

C-4, the US Army designation of the Ford Trimotor.

Citroën C4, a car made by Citroën

C4 is an abbreviation for a four-man Sprint Canoe.

VIA C4, a planned design of central processing unit for a personal computer

C4 (TV channel), a New Zealand television music channel

C4 Engine, a next-generation 3D game engine

USS Philadelphia (C-4), a protected cruiser of the United States Navy

Flip chip packaging is also called Controlled Collapse Chip Connection, or C4

C-4 (explosive), a type of plastic explosive

C-4 Academe, the military version of Gulfstream I twin turboprop business aircraft

C4 (conference), a Macintosh software developers conference

AEG C.IV, a German World War I reconnaissance aircraft

USS C-4 (SS-15), a United States C class submarine of the United States Navy

Middle C in music (American notation)

C4, the envelope size matching the A4 paper size

Ford C4 transmission, an automatic transmission

Cx4 chip, an add-on microprocessor chip for the Super Nintendo system (often incorrectly referred to as the C4 chip)

Complement component 4

HMS C4, a British C class submarine of the Royal Navy

C4 Records, a record label

Fourth cervical vertebra or C4 spinal nerve, in human anatomy

Canadair North Star C-4 aircraft derived from the Douglas DC-4

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