From Wiktionary, the free dictionary
From mis- + defense.
misdefense (uncountable)
- A faulty defense that allows one's opponent to take advantage
2009 January 15, Phillip Alder, “Scrutinizing the Dummy to Develop the Defense”, Bridge, in New York Times[1]:South now had seven tricks (two spades, three hearts and two clubs), and a later misdefense allowed an overtrick.
