Originally Posted by Anneintherain
To clarify, are you looking for a girlfriend, or are you looking for a third? Whenever I hear a third, it's a couple looking for an additional person to be involved with both of them, if you're just looking for a girlfriend I'd be clear and not say that you're looking for a "third", or that language could put people off who don't like the couple's looking for unicorns thing.
Yes, it's a big distinction and of the utmost importance to be clear about. There might might be a few women out there who will go for either, but you're more likely to find them strictly on one side or another of that difference.