Why is hippo a strange word in The Giver?
There are apparently no animals in the "perfect" world of the community. The word "hippo" seems strange to Lily because it names an animal that she has never seen; it does not exist.
When newchildren are born, they are given a "comfort object" to help them settle down when they go to sleep. Lily had received a stuffed elephant, which is kept on a shelf and given to her at bedtime. When she becomes an Eight, her comfort object will be taken away. Many of the comfort objects issued take the form of "soft, stuffed, imaginary creatures", like Lily's elephant, or like Jonas's, which "had been called a bear". These animals do not exist in real life in the Community; they are known only as "imaginary creatures" (Chapter 2).
When Gabe was born, he was issued a hippo as a comfort object. When Father tells Lily what the name of the baby's comfort animal is, she giggles at the strangeness of the word. Lily has neither heard the name before, nor does she know what a hippo is. The little stuffed toy that belongs to Gabriel is the only representation she has ever seen of a hippopotamus (Chapter 3).