In Chapter 8, it begins to snow. Scout has never seen snow before, so she thinks something horrible is happening. According to Eula May, it hasn't snowed since 1885, so Scout would never have had the opportunity to encounter it. Jem and Atticus know enough to know what snow is, but they don't have experience with it either. 

Atticus says, "Looks like all of Maycomb was out tonight, in one way or another," because he realizes that it was Boo Radley who put the blanket on Scout without her noticing. Everyone else in town was helping to tame the spreading fire at Miss Maudie's, including Nathan Radley. Jem and Scout were standing in front of the Radley property, which means they were in prime position for Boo to see how cold they were through his window. 

The "Absolute Morphodite" is how Miss Maudie refers to the snowman in the Finch's yard. Morphodite is another word for hermaphrodite, meaning something that has traits of both sexes. The snowman was originally built to look like Mr. Avery and then disguised with Miss Maudie's hat and shears, making it both a man and a woman.

When Scout hears Miss Maudie call the snowman a morphodite, she only hears it as an insult, and later uses the word against Jem in Chapter 14.

“You damn morphodite, I’ll kill you!”

Scout doesn't understand the true meaning of the word, and instead of asking, she absorbs it, incorrectly, into her vocabulary.