Pronunciation: (mag'num),[key] —n. 1. a large wine bottle having a capacity of two ordinary bottles or 1.5 liters (1.6 quarts).
2. a magnum cartridge or firearm.
—adj. 1. (of a cartridge) equipped with a larger charge than other cartridges of the same size.
2. (of a firearm) using such a cartridge.
3. Informal.unusually great in power or size: a magnum spotlight; a magnum dosage.