BTM vs stern

BTM

• bottom 

stern

• The rear part or after end of a ship or vessel. 

• A bird, the black tern. 

• The tail of an animal; now used only of the tail of a dog. 

• The hinder part of anything. 

• The post of management or direction. 

• To propel or move backward or stern-first in the water. 

• Grim and forbidding in appearance. 

• Having a hardness and severity of nature or manner.