What exactly is an elk? It depends on who you ask, and where you are.
Elk derives from an Old Norse word for the animal Americans call a "moose" (Alces alces). But when European settlers first arrived in the New World, they erroneously applied the label "elk" to the large North American deer they found, when in actuality, those deer were the same species as the European animal known as "red deer" (Cervus elaphus).
To this day, the same animal known as "elk" or "wapiti" (the Native American term) in North America is known as "red deer" in Europe, while the different animal known as "elk" in Europe, is known as "moose" in North America ("moose" also being a Native American term).