The Great Dictionary Caper by Judy Sierra illustrated by Eric Comstock*

Words escape from the dictionary, permitting the reader to examine different types of words.  Noah Webster and Peter Mark Roget are featured. 
Very educational but fun and humorous!
Types of words discussed: onomatopoeia, action verbs, I, contractions, homophones, antonyms, palindromes, archaic words (we loved trying to determine their meanings and then using them in sentences!!), proper nouns, anagrams, rhyming words, words that don't rhyme with anything, interjections, and conjunctions.
A glossary offers formal definitions for the different word categories plus what the archaic words mean.
*Highly recommend.
-Borrowed from the library.