"Oh, say, what is this fearful, wild,
Incorrigible cuss?"
"This creature (don't say 'cuss,' my child;
'Tis slang)—this creature fierce is styled
The Hippopotamus.
His curious name derives its source
From two Greek words: hippos—a horse,
Potamos—river. See?
The river's plain enough, of course;
But why they called that thing a horse,
That's what is Greek to me."

Oliver Herford.