In a Word

http://commons.wikimedia.org/wiki/File:My_Wife_and_My_Mother-in-Law.jpg

pentheraphobia

n. fear of one’s mother-in-law

Above: “My Wife and My Mother-in-Law,” from Puck, November 1915.

Asked what was the maximum punishment for bigamy, Lord Russell of Killowen said, “Two mothers-in-law.”