Indeed, on both counts. And in particular I like the word "rogue planet". Again you have an adjective imparting additional information about another object ("Rogue X"), "rogue" can be readily quantified ("Not in a stable orbit around any particular star or cluster of stars"), and it's a very evocative term. And rogue planets are absolutely expected according to our current models. They'll be incredibly difficult to find, but they're out there.
We're also coming to the realization that there's a lot of objects, potentially including large ones, that are only tenuously bound to our solar system. And it's likely that we readily exchange this mass with other nearby stars over cosmologic timescales; parts of our solar system (primarily distant ones) likely formed by other stars, and things that condensed during the formation of our star system are likely now orbiting other stars.