In the phrase "Good afternoon" what type of word is 'afternoon'?

I've argued that it was a temporal pronoun, but a colleague googled the term "temporal pronoun" and came up with almopst nothing, so I'm now convinced that is an incorrect description.

Is there a category that succinctly describes the temporal part of traditional greeting such as "Good morning", "Good day", "Good night"?

In the phrase "Good afternoon" what type of word is 'afternoon'?

I've argued that it was a temporal pronoun, but a colleague googled the term "temporal pronoun" and came up with almost nothing, so I'm now convinced that is an incorrect description.

Is there a category that succinctly describes the temporal part of traditional greeting such as "Good morning", "Good day", "Good night"?