In the phrase "the massive green dinosaur," what is the head word?

In the phrase "the massive green dinosaur," the head word is "dinosaur." The head word is the main noun that the phrase is describing or providing information about. While "massive" and "green" are adjectives that provide additional detail about the dinosaur, they do not carry the main meaning of the phrase. The article "the" also serves as a determiner but does not contribute to the core meaning of the phrase itself. Therefore, "dinosaur" is the head word because it represents the primary subject of the phrase, with the other words functioning to modify or define it more clearly.