A goose (: geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera Anser (the grey geese and white geese) and Branta (the black geese). Some other birds, mostly related to the shelducks, have "goose" as part of their names. More distantly related members of the family Anatidae are swans, most of which are larger than true geese, and ducks, which are smaller.
The term "goose" may refer to such bird of either sex, but when paired with "gander", refers specifically to a female one (the latter referring to a male). Young birds before fledging are called goslings. The collective noun for a group of geese on the ground is a gaggle; when in flight, they are called a skein, a team, or a wedge; when flying close together, they are called a plump.
The word "goose" is a direct descendant of Proto-Indo-European *ǵhh2éns. In Germanic languages, the root gave Old English gōs with the plural gēs and gandra (becoming Modern English goose, geese, gander, respectively), West Frisian goes, gies and guoske, gans, New High German Gans, Gänse, and Ganter, and Old Norse gās and gæslingr, whence English gosling.
This term also gave žąsìs, gé (goose, from Old Irish géiss), Hindi: कलहंस, anser, Spanish and ganso, Ancient χήν (khēn), gatë (swans), hanhi, Avestan zāō, gęś, gâscă / gânsac, гуска / гусак (huska / husak), гусыня / гусь (gusyna / gus), husa, and (ghāz).
The two living genera of true geese are: Anser, grey geese and white geese, such as the greylag goose and snow goose, and Branta, black geese, such as the Canada goose.
Two genera of geese are only tentatively placed in the Anserinae; they may belong to the shelducks or form a subfamily on their own: Cereopsis, the Cape Barren goose, and Cnemiornis, the prehistoric New Zealand goose. Either these or, more probably, the goose-like coscoroba swan is the closest living relative of the true geese.