Soap-root, which refers to the root of various plants that contains natural saponins and can be used for making soap, has various synonyms. One alternative term for soap-root is soapwort, which is derived from the plant Saponaria officinalis. Another synonym for soap-root is wild quinine, which comes from the Parthenium integrifolium plant. Yucca, a plant that is commonly found in arid regions, is also sometimes referred to as soap-root due to its saponin content. Lastly, the term amole is sometimes used interchangeably with soap-root, although amole specifically refers to the root of the Agave parryi plant. These synonyms help to convey the diversity of plants that offer natural soap-making alternatives.