The term originated from the occasional black sheep which are born into a flock of white sheep due to a genetic process of recessive traits. Black wool was considered commercially undesirable because it could not be dyed. In 18th and 19th century England, the black color of the sheep was seen as the mark of the devil.
The transom is the flat back end of a boat. Some boats are pointed on both ends, so they have no transom. A traditional canoe, pointed on both ends has no transom. A modern square stern canoe (made to take an outboard motor) has a transom.
What Is a Boat Transom? Your boat's transom is a critical part of the hull. The port and starboard sides of your boat are connected by the transom, located at the stern of your boat. Going forward, the two sides of your boat curve together and meet at the bow, forming the shape of the boat's hull. The transom on a small boat typically supports an outboard motor.