Translation

義理の姉 / 義理の妹 / 兄弟の妻

Meaning

The woman married to one's brother or sister. While this phrase is technically accurate, it is rarely used in daily conversation.

Examples

• My sibling's wife organized a wonderful birthday dinner for our mother.
  義理の姉（または妹）が母のために素晴らしい誕生日ディナーを企画してくれました。
• I need to buy a gift for my sibling's wife before the holidays.
  休暇の前に義理の姉（または妹）へのプレゼントを買わなければなりません。