Turkeys derive their name due to confusion over their place of origin when English-speakers first encountered the bird via trade. Turkeys are originally from the Americas and were extensively domesticated before European contact; even the term "wild turkey" is a misnomer.
Turkeys originate from North America. The so-called "wild" turkey served at Thanksgiving in the United States was domesticated in Mexico 2,000 years prior to European contact. The bird was raised and eaten by Aztec and Maya, among other groups. When Spanish war parties arrived to conquer and settle the Americas, they imported the domesticated birds they found there back to Europe.
English-speakers thought the new bird was imported directly from Turkey, although it only arrived via Turkish territory due to convoluted trade routes. The bird was also considered very similar to the guinea fowl, a bird that was indeed imported from Turkish territory, and confusion between the two birds, both supposedly from Turkey, encouraged use of the name.