There are an infinite number of describable concepts that don't get a specific word. That doesn't mean the whole description is a "word with spaces."
It's just part of how language works that when there isn't a single word carrying the meaning you want, you put multiple words together and they can mean the thing together.
Even though there isn't a specific word for that, I wouldn't say "It's just part of how language works that when there isn't a single word carrying the meaning you want, you put multiple words together and they can mean the thing together" actually is one big word with spaces in it.
It's a bunch of words together that carry a more specific meaning when put together in that order.