mesothelioma mes·o·the·li·o·ma (měz'ə-thē'lē-ō'mə, měs'-)
n. pl. mes·o·the·li·o·mas or mes·o·the·li·o·ma·ta (-mə-tə)
A rare neoplasm derived from the lining cells of the pleura and peritoneum and growing as a thick sheet composed of spindle cells or fibrous tissue covering the viscera.