1. [symbol] (chemistry) The relative molecular mass of a molecule.
2. [noun] An abbreviation of mister, a title used before the surname in theory, though not generally in practice, above some undefined social level, too old to be addressed as ?Master?, not a knight or of some higher rank, and, in Britain though not in the United States, not entitled to be addressed as ?Dr?.
3. [noun] (month) March
4. [symbol] Country code for Mauritania (both via ISO 3166-1 alpha-2 and FIPS 10-4).
5. [symbol] World Meteorological Organization country code for Martinique.
6. [symbol] Library of Congress MARC country code for Morocco.
7. [symbol] (metrology) Symbol for the megarayleigh, a unit of measurement of luminous flux, used to measure air glow.
8. [symbol] (metrology) Symbol for the megaröntgen (or megaroentgen), an obsolete unit of measurement of radio-active dose.
9. [noun] A form of address for a man.
