C9
Appearance
C9, C09 or C-9 may refer to:
Medicine/biology
- C9 (Complement component 9), a protein
- ATC code C09, a subgroup of the Anatomical Therapeutic Chemical Classification System
- C09, ICD-10 code for malignant neoplasm of tonsil
Military/weapons
- Hi-Point Models C9 and C9 Comp handguns
- C9 LMG, Canadian light machine gun
- C9, an ID for the German Nachtjagdgeschwader 5 air squadron in World War II
Music
- C9, a note five octaves above Middle C
- C9, a C ninth chord
Organizations
- Cloud9 (esports organization)
- C9 League, a Chinese association of universities
Transportation
- Cierva C.9, a 1927 British experimental autogyro
- HMS C9, a British submarine
- Ford C-9, a US military designation for the Ford Trimotor aircraft
- McDonnell Douglas C-9, a US Air Force transport aircraft based on the civilian DC-9
- USS Montgomery (C-9), a US Navy cruiser
- C9, the IATA code for Cirrus Airlines
- Sauber C9, a Le Mans racing car
- C9 engine, by Caterpillar Inc.
Other uses
- C9, an ISO 216 standard paper size
- C9, a holiday light bulb size
- C9, a sportswear line by Champion