Compound nouns (substantives and adjectives) are divided, according to their meaning, into three main classes: determinative, possessive, and prepositional-phrase, compounds.
a. The logical relation of the parts of compounds varies so greatly that boundary-lines between the different classes are difficult to set up, and a complete formal division is impossible. The poets show a much wider range of usage than the prose-writers.
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].