Korean Family Titles
시누이
sinui · Sister-in-law (husband's sister)
Relationship
my husband → his sister
Who uses it
A wife, about her husband's sister.
When you call them
Her husband's older sister is 형님 (hyeongnim); a younger one is traditionally 아가씨, though many now use her name + 씨.
When you talk about them
To others, 시누이 or 시누.
Example
형님, 저 왔어요!Hyeongnim, I'm here!
Based on the standard etiquette of the National Institute of Korean Language; families and regions vary.