Is there a rule for the two words (which I suppose are nouns) that the second in below example is always at the end?
filling weight (for example of feathers)
stress level
body index
building point
Is there a special name for these nouns as they take part in this kind of phrases? Or does the special name for this kind of phrases?
In general, the first noun is an "attributive noun". It is a noun acting as an adjective. In other words, it is a noun that describes an "attribute" of the other noun.
As sharur points out, the second noun is the "head" of the "noun phrase".
These are examples of "noun phrases", which is a phrase that performs the same grammatical function as a noun in a sentence, generally as a subject, object or prepositional object. It generally consists of a noun or nouns and adjectives and adverbs that modify or describe those nouns and themselves.
For example "the very hungry caterpillar" and "some wildly popular entertainers" are examples of noun phrases.
As a general rule/guideline, if a whole phrase can be replaced in a sentence with a pronoun (in the same way that a noun can be) then that phrase is a noun phrase.
For example, in the sentence "The very hungry caterpillar ate the leaf," the noun phrase can be replaced with the pronoun "it" resulting in "It ate the leaf".
I think you call them compound nouns. It is simply a noun made from two other words.
Usually first word is a qualifier to the second one, Coffee-table, Bedside light, Dartford Tunnel, etc. However the words are just arranged in the specific order they are in (Make-up), and sometimes the two words are hyphenated.
