mid-section
Synonym discussion
Sense: noun/1
For noun/1, mid-section usually describes a visible stretch in the middle of a longer object, such as a bridge, plane, or bottle. Middle is the broad everyday choice and can refer to time, place, or part. Center often suggests a more exact central area and is especially common in American English. Midpoint is more exact still, often used for measurements, routes, or schedules. Core means the inner central part, not simply the area halfway between two ends. If you are describing a person's body, English usually switches to sense 2 or uses a word such as waist or midriff instead.
Etymology
Mid-section was formed in English by joining mid, meaning the middle, with section, meaning a part cut or divided from a whole. The first element goes back to Old English, while section came into English through French from Latin. Together they make a transparent compound for the part halfway between two ends, and the same pattern later came to be used for the waist area of the body.