||Mar*su"pi*um (?), n.; pl. Marsupia (#). [L., a pouch], (Anat. & Zoöl.) (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.