The term animal has its origin from the Latin word animalis which means one who has breath.
This word is usually applied for the non-human members of the Kingdom Animalia in animal taxonomy. However, the closer relatives of humans like mammals (having mammary glands) have been included in this term. Thus cows, bats, rats etc also are mammals.
The biological definition of the word animal refers to all members of the taxonomic kingdom Animalia which incorporates a vast diversity of animals ranging from sponges, insects, whales, elephants and even humans.
Thus, the world of animals is very amazing as it has vast range of diversity in terms of body shape, structure, habitat, feeding habits, and behavior.