Definition of mu in English:



  • 1The twelfth letter of the Greek alphabet (Μ, μ), transliterated as ‘m’.

    • ‘I am also looking to see if Word can do the Greek letter mu, or the Greek symbol for sigma.’
    • ‘In Braille, the same 1-3-4 dot combination designates the letter "mu" in Greek and "mim" in Arabic (both of which have an "m" sound).’
    • ‘Permittivity (denoted by the Greek letter epsilon) is a measure of a material's response to an applied electric field, while permeability (denoted by the letter mu) is a measure of the material's response to an applied magnetic field.’
    1. 1.1Astronomy [followed by Latin genitive] The twelfth star in a constellation:
      ‘Mu Cassiopeiae’
      • ‘Mu Geminorum is a star in the constellation Gemini.’
      • ‘For the rest of this week, asteroid Vesta is within 3 degrees lower left of Mu Virginis.’
    2. 1.2Physics [as modifier] Relating to muons:
      ‘mu particle’

  • 1Micron.

  • 2[in combination] ‘micro-’ in symbols for units:

    ‘the recommended daily amount is 750μg’
  • 3Permeability.