Zoo
It's a short word. It's in every boy or girl's knowledge. You may come across it in most of starter-level school-books of English language. But, strangely, it's not on Ogden's list of 850 Basic words. Why not? Because other words on the list do the work.
"Zoo" is short for "zoological garden," or "garden of zoology." "Zo" came into English from a Greek word for "animal," and "ology" is from a Greek for "science." So "zoology" is animal science.
If you are Japanese, you will see that "zo" is like the old Chinese letter "ju" [獣] for "animal."
Anyway, zoological garden is "garden of animal science." If it's a public garden chiefly for amusement, it will be all right to put "science" away from its name. So "zoo" in Basic English will be
animal garden.