What term is defined as extreme enthusiasm, especially in speech or writing?

The term "rhapsody" refers to a state of intense excitement and enthusiasm, often characterized by elaborate and expressive speech or writing. In literature and music, it conveys a sense of passionate emotion that transcends mere description; it's an overflow of feelings that finds high artistic expression. This aligns perfectly with the question regarding extreme enthusiasm, as rhapsody encapsulates that fervent and ecstatic quality in its usage.

The other terms do not convey the same sense of excitement or enthusiasm. "Refractory" describes something that is stubborn or resistant to control, "querulous" refers to someone who is prone to complaining or whining, and "recalcitrant" indicates a refusal to obey authority or follow rules. None of these options reflects the idea of extreme enthusiasm, making "rhapsody" the apt choice for this definition.