Macropædia
The 17-book Macropædia is the third part of the Encyclopædia Britannica, and the other two parts are the 12-book Micropædia and the 1-book Propædia. The name comes from the word "macro" and "encyclopaedia". Macro means big, and so, the Macropædia is a big encyclopaedia. The Macropaedia has articles that are very detailed, but one article is usually about a very large topic. It is the opposite of the Micropædia, which has articles that are short.