fetus, foetus - an unborn or unhatched vertebrate in the later stages of development showing the main recognizable features of the mature animal

chordate - any animal of the phylum Chordata having a notochord or spinal column

Craniata, subphylum Craniata, subphylum Vertebrata, Vertebrata - fishes; amphibians; reptiles; birds; mammals

Amniota - higher vertebrates (reptiles, birds and mammals) possessing an amnion during development

amniote - any member of the Amniota

aquatic vertebrate - animal living wholly or chiefly in or on water

gnathostome - a vertebrate animal possessing true jaws

bird - warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings

amphibian - cold-blooded vertebrate typically living on land but breeding in water; aquatic larvae undergo metamorphosis into adult form

reptile, reptilian - any cold-blooded vertebrate of the class Reptilia including tortoises turtles snakes lizards alligators crocodiles and extinct forms

mammal - any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milk

tetrapod - a vertebrate animal having four feet or legs or leglike appendages

belly - the underpart of the body of certain vertebrates such as snakes or fish

tail - the posterior part of the body of a vertebrate especially when elongated and extending beyond the trunk or main part of the body

caudal appendage - tail especially of a mammal posterior to and above the anus

costa, rib - any of the 12 pairs of curved arches of bone extending from the spine to or toward the sternum in humans (and similar bones in most vertebrates)

costa, rib - any of the 12 pairs of curved arches of bone extending from the spine to or toward the sternum in humans (and similar bones in most vertebrates)

blood - the fluid (red in vertebrates) that is pumped by the heart; "blood carries oxygen and nutrients to the tissues and carries waste products away"; "the ancients believed that blood was the seat of the emotions"

ovary - (vertebrates) one of usually two organs that produce ova and secrete estrogen and progesterone

chest, pectus, thorax - the part of the human body between the neck and the diaphragm or the corresponding part in other vertebrates

pedal extremity, vertebrate foot - the extremity of the limb in vertebrates

dactyl, digit - a finger or toe in human beings or corresponding part in other vertebrates

endoskeleton - the internal skeleton; bony and cartilaginous structure (especially of vertebrates)

zoological science, zoology - the branch of biology that studies animals