Definition of "MSM"
MSM
noun
countable and uncountable, plural MSM or MSMs
(organic chemistry) Initialism of methylsulfonylmethane.
(media, often derogatory) Initialism of mainstream media.
(uncountable) Initialism of mechanically separated meat.
proper noun
(military, US) Initialism of Meritorious Service Medal.
phrase
(driving) Initialism of mirror, signal, maneuver.