Noun-noun structure; adjectival noun

 

English often uses nouns as adjectives. In all the following, the first noun is serving an adjectival function, and the second noun is the object itself: 

cup handle, glasses case, coat button, kitchen knife, computer screen, information desk, shirt button, umbrella stand, temperature scanner, COVID test, test result,thought experiment,  JCU student, a Camilla essay (i.e. an essay typical of Camilla rather than Camilla's essay, which would be an essay belonging to or written by her), essay plan, floor plan, light switch, window frame  and so on.

It is possible to stack up several nouns, each one of which functions as an adjective until the final one:   

flight information desk, department store changing room, computer motherboard chip, Netflix series trailer, car battery connector cover, composition course teacher,  smartphone screen protector, classroom projection screen, dance music DJ. 

Sometimes they can stretch out a fair bit before they become too long to understand properly, e.g.  garden bird seed feeder hook attachment, cider apple tree root system, digital smart speaker microphone connection slot, Moodle student essay submission button and so on.

Sometimes noun-noun combinations are so common that they  become single words, e.g. heartache,headache, earring, keyboard, toothbrush, desktop, eyebrow, hairbrush, eyeliner, facecloth, saucepan, paperclip, shoelace, headline newspaper, suitcase.

And sometimes they become almost single words that are joined together by a hyphen: face-cream, nose-stud, lip-gloss,  drinks-dispenser, coffee-machine, ice-tray, juice-box, cat-flap. 

Nobody knows how to use hyphens.😕 

Some people would keep the above words completely separate, and others would run them together into a one word. 

The problem is not really the hyphens. The real problem is that  you cannot simply stick one noun in front of another and expect it always to sound natural. You cannot make up   random noun-noun constructions and expect your reader to understand or  simply accept them.  

So before you use  a noun-noun combination, make sure that either (i)  it is already to be a "thing", i.e. an established locution that people already use and therefore find immediately intelligible, or (ii) such a short and/or simple combination that  your reader can accept it without demur even if it is the first time s/he is encountering the combination.   

Combinations that sound "wrong" because they are not established locutions, and therefore their meaning is obscure, might include  something like the following - note how abstract they are: 

topic progression (this is the phrase that inspired this lesson), article assumption, phrase modification, sentence rhetoric, grammar remedy, theory advancement, idea connection, concept line

None of the terms above make any sense without explanation and contextualization.  In each case. you would be better off using propositional phrases (the assumption in the article, the modification of the phrase, etc).