Type 4: Special Noun + Noun – STRESS ON THE SECOND WORD
4d: The thing represented by the compound noun is both the first noun and the second noun, at the same time.
In the 4d. examples, it is quite obvious that the first noun is attempting to express an adjectival idea, more obvious than in the 4a, 4b and 4c examples. In fact, it is possible that some of these originally used adjectives as the first word. For example, possibly "science fiction" was originally "scientific fiction" and "luxury apartment" was originally "luxurious apartment" with the first words having evolved into shorter forms just to make it easier to say them.
However, it seems that most of these 4d examples have nouns as the first word simply because English doesn't have a suitable single adjective to express the exact meaning.
Many of you reading this might not recognize that the first word in these examples is a noun. Even some native English speakers might be confused. The reason for this is that some of these words are so frequently used this way that people start to think of them as adjectives. For example, "waste" in "waste paper" is a noun and "giant" in "Giant Panda" is also a noun. In fact, although my Oxford dictionary says that these (and the other first words in the examples on that page) are nouns, when you go to the MacMillan online dictionary website, you will see that MacMillan is starting to call many of these words both a noun and an adjective. This is an example of language evolution, or at least changes in language classification that reflect the reality of language evolution.
Many of these examples could also fit into the 4e group, which is the group where the first noun represents an adjective. For example, a "a giant tortoise" = a very big tortoise.