ProphDef (also known as The Prophet's Book of Semi-Truthful Definitions) is a dictionary that the Prophet of Lies created at his 8th Year of Prophecy. The book has been passed down to Prophets after him, and is held at a special pocket behind the Prophet's Floating Chair. Each Prophet uses the book when he blanks out and completely forgets a definition of a word, for instance, the Prophet of Truth forgot what Grunts are during National Grunt Appreciation Day, so he looked it up in the ProphDef, which read as "3 year old badasses given weapons about half their size."