The answer to "neck is to scarf" is "waist is to belt." Just as a scarf is worn around the neck, a belt is worn around the waist.
A waist chain is an ornamental chain worn around the waist, seen by some as a symbol of slavery.
A waistcloth is a cloth or garment worn around the waist.
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Is a belt
The traditional garment worn by women in India that typically consists of a string tied around the waist is called a saree.
You would wear it wherever you would wear a tuxedo. A cumberbund is part of the formal wear attire that is an accessory to the tuxedo. & it is worn, by men, around the waist.
A belcher is typically worn around the waist, specifically as a type of belt or girdle. It is designed to provide support and shape to the midsection. In some contexts, it may also refer to a type of jewelry worn around the neck, but the waist is the more common association.
It is called a cincture.
A blouson is a tight garment worn around the waist with blousing over the waistband.
Cummerbund
The fabric is called a "wrapper" or "lappa" and it is a traditional piece of clothing worn by women in various African countries. It is typically worn as a skirt or around the waist in a stylish and elegant manner.