Which term is used to describe a musical sentence?

The term that describes a musical sentence is "phrase." In music, a phrase typically consists of a series of notes that form a coherent musical thought, much like a sentence in language. Phrases often have a beginning and an end, and they're often identified by natural breaks or cadences that give them a sense of completion.

To understand this concept in a broader context, it’s helpful to distinguish it from other terms. A measure refers to a specific unit of time in musical notation defined by a bar line, while a cadence is a progression of chords that concludes a phrase or section, often leading to a sense of resolution. Lastly, a section is a larger division of a piece of music that can consist of multiple phrases. Thus, "phrase" is the most accurate term to describe a standalone musical sentence.