The twenty-fifth entry in the Words Are CATegorical series once again pairs rhymed examples and explanations to cartoon scenes featuring well-caffeinated cats in a range of costumes and unnatural colors acting out the suggested meanings. As with previous books, it's not a systematic survey but rather a quick skim quick that some common suffixes, such as -ism and -ology, are left out, and others that do appear (specifically -ward, -ation, and -ery) aren't picked up in the closing summary chart. Cleary mentions root words but steers clear of more advanced topics such as parts of speech, contractions (which are covered elsewhere), or inflectional versus derivational suffixes. Vague as the guidelines sometimes are ("N-E-S-S often shows / a certain quality, / Like awkwardness / and happiness / and kindness, to name three"), younger readers, or older ones less familiar with the language, will come away with at least a sense of what these slippery lexical items look like and some of the purposes they serve.

Cleary's hyperactive rhymes introduce the language concept. While the definition of suffix provided isn't satisfying, the many examples will help kids begin to understand the term's various meanings and functions in words. The illustrations of zany cats are humorous but distracting; the spreads with embedded charts are most helpful in supporting the text. A final chart with suffixes, meanings, and examples is appended.