Interlisted Stock
  
You’re looking to meet that special someone. You sign up for Match.com, JDate, Tinder, OkCupid, and eHarmony. You are...interlisted.
Similarly, a stock is interlisted if it trades on more than one exchange. If a stock lists on both the NYSE and the Toronto Stock Exchange, for example, it would be considered an interlisted stock.
Why would you do this? Simple: you want as many people as possible to easily be able to buy your stock.
See: Market Liquidity.