This recent Family Circus cartoon shows Billy consulting a dictionary and being surprised at what it says about the word verb:
Why does Billy find this weird?
Because, already at the age of 7, he's absorbed the Semantic Essence theory of parts of speech, the idea that BY DEFINITION verbs are action words, nouns name persons, places, or things, and so on. If you accept this, and are none too clear about the difference between words and their meanings, then you'll expect verb to be a verb; the dictionary part-of-speech classification will seem paradoxical to you.
The Semantic Essence theory plays a central role in the "X is a verb" snowclone (conveying that the word X — usually a noun, but sometimes an adjective — denotes an action) — first discussed here (on faith) and here (on baptism) as a trope, labeled a snowclone here (on science), and (I think) most recently discussed on Language Log here (on gay). This snowclone tends to annoy linguists. Yes, we understand it's not to be understood literally, but we sigh in dismay at the fact that the metaphor in the snowclone hinges on Semantic Essence. And despite the fact that almost every discussion of grammar outside of the field of linguistics (in particular, treatments in textbooks and advice manuals) explicitly adheres to Semantic Essence, the idea is flat wrong. As Geoff Pullum said in his posting on science:
It absolutely is not the case that you can coherently define lexical categories this way — nouns as words that name things, verbs as words for actions, adjectives as words for qualities, prepositions as words for relations between things, and so on. It simply does not work. It part of an ancient theory of grammar that is not just sick but dead on arrival, like the phlogiston theory of combustion. Only grammar never had its chemical revolution as far as the general public is concerned.