Learner's definition of WAIST
the middle part of your body between the hips and chest or upper back that is usually narrower than the areas above and below it
see picture at human
He has a narrow waist and broad shoulders.
He put his arm around her waist.
They lay in the sun naked from the waist up. = They lay in the sun stripped to the waist.
paralyzed from the waist down = paralyzed below the waist
the part of a piece of clothing that fits around your waist
— usually used in combination