The term 'hippo' is a shortened version of the word 'HIPPOPOTAMUS, ' which is a large, semi-aquatic mammal native to Africa. The two crossword solutions for this term are 'PYGMY' and 'riverhorse.' PYGMY is a five-letter word that refers to a group of people who are characterized by their short stature. Riverhorse is a ten-letter word that is another name for the HIPPOPOTAMUS, as it spends much of its time in rivers and other bodies of water.