Final answer:
The best reference book to look for the meaning of the word 'naive' would be a dictionary.
Step-by-step explanation:
When looking for the meaning of the word 'naive', the best reference book to consult would be a dictionary. A dictionary provides a description of how a word is commonly used in everyday speech, allowing you to understand its meaning and usage. However, it's important to note that a dictionary definition may not capture the full depth or nuances of a word, so additional research or context may be needed.