\Mar*su"pi*um\, n.; pl. {Marsupia}. [L., a pouch],
(Anat. & Zo["o]l.)
(a) The pouch, formed by a fold of the skin of the abdomen,
    in which marsupials carry their young; also, a pouch for
    similar use in other animals, as certain Crustacea.
(b) The pecten in the eye of birds and reptiles. See
    {Pecten}.