The story
From sister + -out-law, by analogy to sister-in-law.
Etymology from Wiktionary, CC BY-SA 4.0.
sister-out-law
Today it means: The sister of one's boyfriend or girlfriend. Full definition →
Today it means: The sister of one's boyfriend or girlfriend. Full definition →
From sister + -out-law, by analogy to sister-in-law.
Etymology from Wiktionary, CC BY-SA 4.0.