The term "Sisters-in-law" refers to the wives of one's siblings or the sisters of one's spouse. However, there are several synonyms that can be used in place of this term. One term is "Sibling-in-laws," which refers to the family relationship between siblings and their spouses. Another synonym for "Sisters-in-law" is "In-laws sisters," which refers to the sisters of one's spouse. The term "Spousal siblings" also refers to siblings who are married to someone else. Lastly, the term "Brother's wife" can be used to refer to the sister-in-law who is married to one's brother. These synonyms provide options to avoid repetition and add variety to the language.