What melodic term describes the stepwise progression between chord tones?

The term that best describes the stepwise progression between chord tones is "Melodic Motion." This concept specifically refers to how melodies move from one pitch to another, particularly in a smooth, stepwise manner—such as moving up or down by seconds—between the notes that make up a chord.

In the context of melody, such motion can create a sense of direction and flow and is fundamental in shaping a melodic line. When describing movement related to chord tones, melodic motion highlights the transitions and connections between notes, linking harmonically relevant pitches in a way that enhances musical expression and coherence.

Scale degree pertains to the specific position of notes within a scale and does not directly address the movement between chord tones. The tonal center refers to the central or "home" pitch around which a piece of music is structured, and harmony typically describes the simultaneous combination of different musical pitches or chords rather than the movement between individual notes. Therefore, while each term has its relevance in music theory, "Melodic Motion" is the most accurate in the context of describing the stepwise progression between chord tones.