muPronunciation: /mjuː/Definition of mu noun the twelfth letter of the Greek alphabet (Μ, μ), transliterated as ‘m’. (Mu) [followed by Latin genitive] Astronomy the twelfth star in a constellation:Mu Cassiopeiae [as modifier] Physics relating to muons:mu particle symbol (μ) micron. (μ) [in combination] ‘micro-’ in symbols for units:the recommended daily amount is 750μg (μ) permeability. Origin:Greekmu in other Oxford dictionaries Definition of mu in the US English dictionary
