C1

C1, C01, C.I or C-1 may refer to:

Arts and media

 * C1, a note-octave in music
 * C1 Television, a Mongolian television channel
 * Schecter C-1 Hellraiser FR, a guitar model
 * A Yamaha grand piano model
 * "C1", a slang expression in the video game Counter-Strike, used to express agreement

Anatomy

 * Cervical vertebra 1, the first cervical vertebrae of the vertebral column
 * Cervical spinal nerve 1, a spinal nerve of the cervical segment

Biochemistry

 * C1 complex, the first component of the classical complement pathway
 * C1 domain, an important secondary messenger protein domain
 * C1-inhibitor, a human serine protease inhibitor
 * C1 regulatory sequence for the insulin gene
 * Apolipoprotein C1, a human lipoprotein
 * Chlorophyll c1, a form of chlorophyll
 * Cytochrome C1, a precursor protein to Cytochrome C
 * Proanthocyanidin C1, a type of polyphenolic compound
 * Prostaglandin C1, a form of prostaglandins

Other uses in biology and medicine

 * C1 and P1 (neuroscience), a component of the visual evoked potential
 * ATC code C01, a subgroup of the Anatomical Therapeutic Chemical Classification System
 * C01, the ICD-10 code for "malignant neoplasm of base of tongue", a form of oral cancer
 * C1, the short name for a microfluidic single-cell analysis system sold by Fluidigm

Chemistry

 * C1 Chemistry, study of methane, methanol, carbon monoxide, carbon dioxide

Hardware

 * C-One, a single-board microcomputer
 * C1 NES TV, a family of Nintendo-television-set hybrids manufactured by Sharp Corporation in 1983
 * ATI C1, codename of the Xbox 360 GPU Xenos

Other uses in computing

 * C0 and C1 control codes defined in ISO 6429
 * C1 (protocol), a 1984 protocol for file transfer, also known as "Punter"
 * TCSEC C1 security class
 * A CPU power state in the Advanced Configuration and Power Interface

Mathematics

 * $$C^1$$, the set of all continuously differentiable functions
 * C1 field, a quasi-algebraically closed field
 * C1, the first of four pure modules taken in the Advanced Level (UK) Maths syllabus

Air

 * C-1 Trader, a cargo-version of the S-2 Tracker anti-submarine warfare aircraft of the United States Navy
 * AEG C.I, a German World War I reconnaissance aircraft
 * AGO C.I, a 1915 German reconnaissance biplane
 * Albatros C.I, a 1915 German two-seat general-purpose biplane
 * Aviatik C.I, a 1915 German observation plane
 * Cierva C.1, a 1920 Spanish experimental autogyro
 * DFW C.I, a WWI German reconnaissance aircraft
 * Douglas C-1, a cargo/transport airplane produced by Douglas Aircraft for the U.S. Army Air Service starting in 1925
 * Fokker C.I, a 1918 German reconnaissance biplane
 * Friedrichshafen C.I, a 1914 German single-engined amphibious reconnaissance biplane
 * Hansa-Brandenburg C.I, a 1916 German 2-seater armed single-engine reconnaissance biplane
 * Kawasaki C-1, an indigenous transport aircraft of the Japanese Air Self-Defense Forces
 * Otto C.I, a 1915 German reconnaissance biplane
 * Rumpler C.I, a 1915 German two-seater single-engine reconnaissance biplane
 * Southern Cross Airport (New Jersey) (FAA LID: C01)

Routes

 * Circumferential Road 1 or C-1, an arterial road of Manila, Philippines
 * London Buses route C1
 * Route C1 (Shuto Expressway), the Inner Loop of Tokyo's Shuto Expressway system
 * Claro M. Recto Avenue, a road in Metro Manila, Philippines
 * Massachusetts State Route C1

Land vehicles

 * BMW C1, a cabin scooter
 * Chevrolet Corvette C1, first generation sold from 1953 to 1962, denoted a solid-axle rear-end
 * Citroën C1, a small car
 * Ford C1 platform, the Ford Motor Company's global compact car automobile platform
 * Leapmotor C01, a battery electric executive sedan
 * Lit C-1, a prototype cabin motorcycle
 * Nimrod NRA/C1, a 1981 test design racing car
 * Sauber C1, a Sauber sport car

Other uses in land transport

 * C-1, the numberplate of the Prime Minister of Australia's official VIP transportation
 * A type of heavy goods vehicle licence
 * A one-way traffic sign in the Vienna Convention on Road Signs and Signals

Rail

 * Bavarian C I, an 1847 German steam locomotives class
 * GNR Class C1 (small boiler), a British 4-4-2 steam locomotive class (classified C2 during LNER ownership)
 * GNR Class C1 (large boiler), a British 4-4-2 steam locomotive class
 * LB&SCR C1 class, an 1882 British freight steam locomotive
 * Long Island Rail Road C1, a bilevel railcar built by Tokyu Car Corporation
 * NER Class C1, a British 0-6-0 steam locomotive class
 * PRR C1, an American PRR steam locomotive
 * Finnish Steam Locomotive Class C1

Sea

 * HMS C1, a C-class submarine of the Royal Navy
 * USS C-1 (SS-9), a C-class submarine of the United States Navy
 * USS Newark (C-1), a protected cruiser of the United States Navy
 * Type C1 ship, a small cargo vessel built by the United States in large numbers before and during World War II
 * Isaac Peral (C-1), a Spanish submarine

Space

 * Cluster 1, also known as Rumba, an ESA satellite

Sports

 * C1, a solo canoe discipline including sprint canoe and canoe slalom
 * C1 (classification), a para-cycling classification
 * C1, an abbreviation for Class One offshore powerboat racing
 * 'C1', the top category in Group C sportscar racing, used between 1985 and 1990
 * C1, the UEFA Champions League (formerly known as the European Cup) in football
 * Serie C1, the third highest football league in Italy until 2008

Other uses

 * C1, an international standard paper size defined in ISO 216 (648×917 mm)
 * Bills C-1 and S-1, a pro forma bill normally introduced at the start of a parliamentary session in the Canadian House of Commons
 * C1, also known as Vlakplaas, a unit of the South African Police responsible for assassinating opponents of Apartheid during the 1980s
 * C1, a level in the Common European Framework of Reference for Languages
 * C1, the use class for hotels, in town and country planning in the United Kingdom
 * C1, a NRS social grade in the United Kingdom for the lower middle class
 * a 2001 1.3 megapixels Olympus digital camera model
 * a class of FM radio broadcasting in North America
 * C1 pylon, a type of high voltage pylon
 * Caldwell 1 (NGC 188), an open cluster in Cepheus
 * C-1 visa, a type of visa for individuals transiting through the United States
 * C1 Espresso, café in Christchurch, New Zealand