Explain why miss maudie laughs when scout uses the word morphodite to describe the snowman

Miss Maudie laughs because Scout has used the wrong word.

Miss Maudie and Atticus earlier described the snowman as a "hermaphrodite." Scout overheard their conversation. Later, when she wanted to use the word herself, she bungled the pronunciation and sad "morphodite" instead of the correct version.

Miss Maudie laughs because Scout not only used the wrong word but came up with a funny alternative. Neither Jem nor Scout understands why she is laughing, though.