What term describes a fever that remains constant above the baseline without fluctuation?

The term that describes a fever that remains constant above the baseline without fluctuation is "continuous." This type of fever does not exhibit significant temperature variation throughout the day, unlike intermittent or remittent fevers, which may fluctuate or return to normal at certain times. Continuous fever is often seen in infections or inflammatory processes where the body's temperature regulation is altered but remains consistently elevated.

Although "pyrexia" refers to the state of having a fever, it does not specify the pattern or consistency of the fever itself, which makes it less precise in this context. "Hyperpyrexia" refers to an extremely high fever, usually above 106°F (41.1°C), but again lacks the detail about the consistency. "Apnea" is unrelated as it refers to the absence of breathing. Hence, "continuous" is the term that accurately captures the characteristic of a fever that does not fluctuate and remains sustained above the normal baseline.