sister-out-law

plural sisters-out-law

1. The sister of one's boyfriend or girlfriend.
2. Girlfriend of one's brother or sister.

   “If you're openly gay, wouldn't that make you his sister-out-law?”

   2014, Janice Ryan Hall, Deadly Ties: Sequel to Blood Ties, volume 2 (Fiction), →ISBN, D1dXDQAAQBAJ, page 565

   3 more examples

   I, on the other side, was ready to strangle my almost sister-in-law. (My sister out-law.)

   2008, John Crawley, Among the Aspen, →ISBN, TDrcNfNKVH4C, page 114

   This included Prunella Tuff, my “sister-out-law”, a term we invented to describe the relationship between us as she was the sister of my brother in-law, Tim Tuff.

   2013, Howard Balloch, Semi-Nomadic Anecdotes (Biography & Autobiography), →ISBN, jwc6BgAAQBAJ, page 59

   I, on the other side, was ready to strangle my almost sister-in-law. (My sister out-law.)

   2015, Katherine Woodward Thomas, Conscious Uncoupling: 5 Steps to Living Happily Even After (Family & Relationships), →ISBN, 2pv0BQAAQBAJ, page 59

3. The sister of one's ex-spouse.