Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
double-magnum is a noun meaning "a large wine bottle (holds 4/5 of a gallon)". It carries one recorded sense.
a large wine bottle (holds 4/5 of a gallon)
Definitions, synonyms and semantic relations for double-magnum come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.