What do you have in common with your hamster, a whale, a bat, a giraffe, and the kid who packs your groceries? Every one is a mammal — a hairy, warm-blooded, milk-drinking vertebrate, just like you.

All mammals are part of the scientific class mammalian, which got its name from the mammary glands used to nourish mammal babies. A note of interest: although a characteristic of mammals is that babies are born live, there’s a group of mammals called monotremes, like the platypus, that lay eggs; but whose young’uns, after they hatch, still get fed mama’s milk. Go figure.

Definitions of mammal
  1. noun
    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
    synonyms: mammalian
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    incomplete skeleton of female found in eastern Ethiopia in 1974
    Sir Barton
    thoroughbred that won the triple crown in 1919
    Gallant Fox
    thoroughbred that won the triple crown in 1930
    thoroughbred that won the triple crown in 1935
    War Admiral
    thoroughbred that won the triple crown in 1937
    thoroughbred that won the triple crown in 1941
    Count Fleet
    thoroughbred that won the triple crown in 1943
    thoroughbred that won the triple crown in 1946
    thoroughbred that won the triple crown in 1948
    thoroughbred that won the triple crown in 1973
    Seattle Slew
    thoroughbred that won the triple crown in 1977
    thoroughbred that won the triple crown in 1978
    show 38 types...
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    female mammal
    animals that nourish their young with milk
    any mammal with prominent tusks (especially an elephant or wild boar)
    primitive oviparous mammals found only in Australia and Tasmania and New Guinea
    primitive pouched mammals found mainly in Australia and the Americas
    eutherian, eutherian mammal, placental, placental mammal
    mammals having a placenta; all mammals except monotremes and marsupials
    fossorial mammal
    a burrowing mammal having limbs adapted for digging
    egg-laying mammal, monotreme
    the most primitive mammals comprising the only extant members of the subclass Prototheria
    marsupial, pouched mammal
    mammals of which the females have a pouch (the marsupium) containing the teats where the young are fed and carried
    farm animal, livestock, stock
    any animals kept for use or profit
    mature male of various mammals of which the female is called `cow'; e.g. whales or elephants or especially cattle
    mature female of mammals of which the male is called `bull'
    an animal in its second year
    mature male of various mammals (especially deer or antelope)
    mature female of mammals of which the male is called `buck'
    small insect-eating mainly nocturnal terrestrial or fossorial mammals
    aquatic mammal
    whales and dolphins; manatees and dugongs; walruses; seals
    a terrestrial or aquatic flesh-eating mammal
    in some classifications considered a suborder of Carnivora
    Orycteropus afer, aardvark, ant bear, anteater
    nocturnal burrowing mammal of the grasslands of Africa that feeds on termites; sole extant representative of the order Tubulidentata
    bat, chiropteran
    nocturnal mouselike mammal with forelimbs modified to form membranous wings and anatomical adaptations for echolocation by which they navigate
    gnawing mammal, lagomorph
    relative large gnawing animals; distinguished from rodents by having two pairs of upper incisors specialized for gnawing
    gnawer, rodent
    relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing
    naked mole rat
    fetal-looking colonial rodent of East Africa; neither mole nor rat; they feed on tubers and have a social structure similar to that of honeybees and termites
    Damaraland mole rat
    colonial mole rat of western Africa; similar to naked mole rat
    in former classifications a major division of Mammalia comprising all hoofed mammals; now divided into the orders Perissodactyla (odd-toed ungulates) and Artiodactyla (even-toed ungulates)
    hoofed mammal, ungulate
    any of a number of mammals with hooves that are superficially similar but not necessarily closely related taxonomically
    in former classifications a major division of Mammalia comprising mammals with nails or claws; distinguished from hoofed mammals and cetaceans
    unguiculate, unguiculate mammal
    a mammal having nails or claws
    coney, cony, das, dassie, hyrax
    any of several small ungulate mammals of Africa and Asia with rodent-like incisors and feet with hooflike toes
    any of various nonruminant hoofed mammals having very thick skin: elephant; rhinoceros; hippopotamus
    primitive terrestrial mammal with few if any teeth; of tropical Central America and South America
    anteater, pangolin, scaly anteater
    toothless mammal of southern Africa and Asia having a body covered with horny scales and a long snout for feeding on ants and termites
    any placental mammal of the order Primates; has good eyesight and flexible hands and feet
    tree shrew
    insectivorous arboreal mammal of southeast Asia that resembles a squirrel with large eyes and long sharp snout
    colugo, flying cat, flying lemur
    arboreal nocturnal mammal of southeast Asia and the Philippines resembling a lemur and having a fold of skin on each side from neck to tail that is used for long gliding leaps
    proboscidean, proboscidian
    massive herbivorous mammals having tusks and a long trunk
    plantigrade, plantigrade mammal
    an animal that walks with the entire sole of the foot touching the ground as e.g. bears and human beings
    digitigrade, digitigrade mammal
    an animal that walks so that only the toes touch the ground as e.g. dogs and cats and horses
    type of:
    craniate, vertebrate
    animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium
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