shag2Pronunciation: /ʃaɡ/Definition of shag noun a western European and Mediterranean cormorant with greenish-black plumage and a long curly crest in the breeding season. Phalacrocorax aristotelis, family Phalacrocoracidae chiefly NZ any cormorant. Phrases like a shag on a rock Australian informal in an isolated or exposed position. Origin: mid 16th century: perhaps a use of shag1, with reference to the bird's ‘shaggy’ crestshag in other Oxford dictionaries Definition of shag in the US English dictionary