M81 or M-81 may refer to:
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M-81 (Michigan highway)
M-81 is an east–west state trunkline highway in the Lower Peninsula of the US state of Michigan. The trunkline travels from the city of Saginaw at the junction with M-13 to the junction with M-53 east of Cass City over the county line in ...
, a state highway in Michigan
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McDonnell-Douglas MD81
The McDonnell Douglas MD-80 is a series of five-abreast narrow-body aircraft, single-aisle airliners developed by McDonnell Douglas. It was produced by the developer company until August 1997 and then by Boeing Commercial Airplanes. The MD-80 ...
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Messier 81
Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a grand design spiral galaxy about 1 E22 m, 12 million light-years away in the constellation Ursa Major. It has a Galaxy#Isophotal diameter, D25 isophotal diameter of . Because of its rela ...
, a spiral galaxy in the constellation Ursa Major, also known as NGC 3031 or Bode's Galaxy
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U.S. Woodland, a camouflage pattern colloquially known as "M81"
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