C81 or C-81 may refer to :
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''C81'' (album) (1981)
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C-81 (Michigan county highway)
The county-designated highways in Michigan comprise a system of primary county roads across the US state of Michigan. Unlike the Michigan State Trunkline Highway System, State Trunkline Highway System, these highways have alphanumeric designatio ...
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C-81 Reliant, a 1933 military aircraft
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Campbell Airport's FAA LID code
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Hodgkin's lymphoma
Hodgkin lymphoma (HL) is a type of lymphoma in which cancer originates from a specific type of white blood cell called lymphocytes, where multinucleated Reed–Sternberg cells (RS cells) are present in the lymph nodes. The condition was named a ...
's ICD-10 code
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NGC 6352
NGC 6352 (also known as Caldwell 81) is a globular cluster of stars in the southern constellation of Ara, located approximately from the Sun. It was discovered by Scottish astronomer James Dunlop on May 14, 1826. The cluster has a Shapley–S ...
's Caldwell catalog number
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Ruy Lopez
The Ruy Lopez (; ), also called the Spanish Opening or Spanish Game, is a chess opening characterised by the moves:
:1. e4 e5
:2. Nf3 Nc6
:3. Bb5
The Ruy Lopez remains one of the most popular chess openings, featuring many variations. In ...
's Encyclopaedia of Chess Openings code
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