• (n.) A large grackle or blackbird (Quiscalus major), found in the Southern United States.
A transition section at the tail of a rocket (or other vehicle) that gradually narrows the body down to the motor diameter. It thereby helps reduce base drag.
Boat'-tail` noun (Zoology) A large grackle or blackbird ( Quiscalus major ), found in the Southern United States. 
a body style in which the rear end of the vehicle tapers to a point or a cone.