Definition of "returnable"

At last, as the discussion with the Flat-Earthers was becoming acrimonious, Ollie spoke up. “If you don’t believe it, Norton, that’s fine. I’ll tell you what to do. You go on out that front door and walk around to the back. There’s a great big pile of returnable beer and soda bottles there. Norm and Buddy and I put them out this morning. You bring back a couple of those bottles so we know you really went back there. You do that and I’ll personally take my shirt off and eat it.” […] But [Norton] didn’t take Ollie up on his offer to bring back a sampling of returnables from out back. None of them did.

1980, Stephen King, The Mist