Final answer:
The term 'transverse' refers to an imaging orientation where the image's long dimension is perpendicular to the body's long axis, resulting in a horizontal division into upper and lower portions.
Step-by-step explanation:
The term that describes an imaging orientation where the long dimension of the image is perpendicular to the long axis of the body is transverse. A transverse plane (or horizontal plane) divides the body or an organ into upper and lower portions, producing images known as cross sections. This is different from the midsagittal plane, which cuts the body into equal right and left halves, and the coronal plane, which separates the front (ventral) from the back (dorsal). The transverse orientation is sometimes also referred to as a horizontal cross-section.