Korean Family Titles
시아버지
siabeoji · Father-in-law (husband's father)
Relationship
my husband → his father
Who uses it
A wife, about her husband's father.
When you call them
Call him 아버님 (abeonim).
When you talk about them
To others, 시아버지 or 저희 시아버지.
Example
아버님, 이번 주말에 찾아뵐게요.Father, we'll come and see you this weekend.
Based on the standard etiquette of the National Institute of Korean Language; families and regions vary.