noun: (games) A marble (glass ball used in games), especially one used as a target.
noun: (in the plural) A game of marbles.
noun: (US, ufology, conspiracy theorists) Initialism of man in black. [(sports, informal) The referee.]
noun: (US, in the plural) Initialism of men in black.
noun: (organic chemistry) Initialism of methylisoborneol. [(organic chemistry) Any methylated derivative of isoborneol, but especially (1R,3R,4R)-3,4,7,7-tetramethylbicyclo[2.2.1]heptan-3-ol]
