throw-in (Noun) — (rugby) an act or instance of throwing a ball in to put it into play.
throw-in (Verb) — Add as an extra or as a gratuity.
throw-in (Verb) — Give up in the face of defeat of lacking hope; admit defeat. ex. "In the second round, the challenger threw in the towel"
throw-in (Verb) — To insert between other elements. ex. "She threw in clever remarks"