What does the term "slur" indicate in musical performance?

The term "slur" in musical performance indicates that notes are to be played smoothly, connecting them without any separation or break. This stylistic directive creates a seamless transition from one note to the next, giving the music a flowing characteristic. When musicians see a slur marking over a group of notes, they understand they should play those notes legato, emphasizing a smooth, connected sound rather than articulating each note distinctly.

In the context of the other choices, playing notes detached refers to a different articulation technique, typically indicated by staccato markings, while playing louder pertains to dynamics rather than articulation. Repeating notes would also not be linked to the concept of a slur, which focuses on the connection and flow between notes rather than repetition.