M51
M51 , M 51 or M-51 stands for:
- Messier 51, a spiral galaxy, see Whirlpool galaxy
- a trunk road in Russia and Kazakhstan, see R254 (Russia)
- a motorway in Hungary, see Autópálya M51
- a street in the US state of Michigan, see M-51 (Michigan)
- BMW M51 , a six-cylinder diesel engine from BMW
- Revox M51, an audio-video system, see Revox #Current Electronics
- M 51 (MSBS) , a submarine-based nuclear ICBM
- an anti-aircraft gun, see M51 Skysweeper
- Metro line 51 (Amsterdam) , a subway line of the Amsterdam Metro
