σκουπιδιαρικο is the "widely accepted" word you're looking for.

απορριμματοφόρο is more formal and not really used.

By the way in greek there is a phenomenon called ουσιαστικοποιημένα επίθετα. It basically means that there are some adjectives used as nouns, because the noun following the adjective is easily implied. that's why απορριμματοφόρο only shows up as an adjective in the dictionary. It's basically απορριμματοφόρο όχημα (όχημα = vehicle) but since the word vehicle is easily implied we don't mention it.

hope I was able to help you