Final Answer:
The word for a U-shaped bend in a stream's course, also used to describe taking a winding course, is derived from a Turkish river:
d) Meander
Step-by-step explanation:
The term "meander" originates from the Meander River in Turkey, known for its winding and circuitous path. Over time, this term has been adopted into the English language to describe a U-shaped bend or a winding course, both in geographical contexts and more broadly in language.
The other options, such as the Euphrates, Tigris, and Bosphorus, are also geographically significant features, but they are not directly associated with the term "meander."