MGY or a variant thereof is used as an abbreviation for: Megagray (MGy) and milligray (mGy), SI derived units of the gray (absorbed radiation dose) mgy, MGY, mmgy, MMgy, or MMGY: Million gallons per year
MGY as an identifier has been used to denote: Dayton-Wright Brothers Airport, IATA code Montgomeryshire, historic county in Wales, Chapman code The maritime call sign of RMS Titanic's radiotelegraph station
MGY may also refer to: MG Y-type, an MG car