What it used to be called:
Disposables soaked up most of the market.
Centuries ago, the word diaper had nothing to do with bottoms. It referred to a fabric with a distinctive geometric pattern. This kind of fabric was used in the garment for babies; that garment came to be known as a diaper.
These days diaper generally means the disposable kind an invention that first appeared after World War II.
When the language required a new word for the old thing, cloth diaper was born.
An early use:
"Playtex tests confirmed by the Good Housekeeping Institute show that Dryper disposable diapers are more absorbent than ordinary cloth diapers." Advertisement, Los Angeles Times, July 12 1960