From Longman Dictionary of Contemporary Englishgannetgan‧net /ˈɡænɪt/ noun [countable] 1 
HBBa large sea bird that lives in large groups on cliffs2 British English informalEAT someone who eats a lot
HBBa large sea bird that lives in large groups on cliffs2 British English informalEAT someone who eats a lotExamples from the Corpus
gannet• This applies mainly to the opportunist feeders like gulls, fulmars, skuas and to some extent gannets.• Fulmars, gannets and an occasional storm petrel performed aerobatics in our wake.• Then an immature gannet came into view away out at sea, a huge bird, still in mottled dark brown plumage.• In spring those cliffs are alive with auks and gulls, and my favourite bird, the gannet.• But the gannets of Bempton Cliffs are within easy reach of all.• Far out to sea lies the gannet colony of Grassholm.• Here they would spend ten or more days catching the young gannets which breed on the rock in thousands.• Young gannets are brown, very much like young seagulls, and have white cheeks.Origin gannet Old English ganot 