[医] 后生动物(有时指复细胞动物)

[ noun ]
multicellular animals having cells differentiated into tissues and organs and usually a digestive cavity and nervous system
<noun.animal>

Metazoa \Met`a*zo"a\, n. pl. [NL., fr. Gr. ? after + zo^,on an
animal.] (Zo["o]l.)
Those animals in which the protoplasmic mass, constituting
the egg, is converted into a multitude of cells, which are
metamorphosed into the tissues of the body. A central cavity
is commonly developed, and the cells around it are at first
arranged in two layers, -- the ectoderm and endoderm. The
group comprises nearly all animals except the Protozoa.