Is trash a noun or adjective?

"Trash" can be both a noun and an adjective, depending on how it's used:

Noun:

* Meaning: Waste material, garbage.

* Example: "The trash can was overflowing."

Adjective:

* Meaning: Of low quality, worthless, or useless.

* Example: "That movie was trash."

So, the answer to your question is: Both!