Disclaimer: The country of Turkey is amazing, with a beautiful culture and a very impressive and long history. This post is not intended to be irreverent, but to simply answer a question that many of us may be holding back because we realize how silly it sounds.
While I have not personally performed extensive research on the topic, here is one answer to this question from dictionary.com. Essentially, this post says that similar birds were exported to Europe through the Ottoman Empire and were therefore called "turkey-hens" or "turkey-cocks." So when these birds were exported from the US to Europe, they were then called turkeys. While the country was not called Turkey at that time, the Turkic people were called Turks.
I will leave it to you to decide whether this account is fact or fiction. In any case, it is something to discuss tonight over your Thanksgiving meal, or when eating leftovers tomorrow.
I remember one Thanksgiving that I spent away from the US, when I was living in the country of Turkey, working for the International Finance Corporation/World Bank Group. This particular Thanksgiving was the first that I spent with the Turkish man who is now my husband. I really wanted him to get a glimpse of this holiday that was (and is) so important for me. So I went to great lengths to procure three large turkey legs which were already cooked from a local restaurant. We had them alongside a side of noodles baked in bechamel sauce which reminded me a lot of macaroni and cheese. This year, I am grateful to be living back at home in the US and to be sharing a beautiful, full Thanksgiving meal with my family, including my husband who has come back to the US with me from the country of Turkey.
Happy Thanksgiving! Thank you for reading my blog, I truly appreciate it.