Example: polar bear
I can only detect polar as an adjective and bear as a noun. But polar bear is actually a “noun”. How do I obtain a free list of such?
Another example: hot dog.
One thing that might help you is to know that often when an adjective and noun are combined to become a noun, there is a hyphen between the words, though the hyphen tends to get dropped as the compound comes into more general usage. The spellcheck on your computer may give you. I can’t document this, but it seems to me that spellchecks tend to lag a bit behind general usage and keep the hyphen longer. Otherwise you just have to go with common sense and the context in which the words are used.