Here's a definition: A Lomcovak is NOT an inverted spin. It is NOT a non-precision maneuver. The pilot is NOT "just along for the ride". Recovery does NOT just occur at random without any control by the pilot. It is NOT a single maneuver, but rather an entire family of maneuvers, all of which are very precise and controlled from beginning to end IF they are properly done.
The key element in a Lomcovak is that the airplane's attitude and motion is controlled by four primary flight controls rather than the usual three. The fourth attitude control in this case is gyroscopic precession from the prop, controlled via the throttle. This is why it's extremely difficult (that's spelled i-m-p-o-s-s-i-b-l-e) to do a true Lomcovak with a model; in most cases our props simply aren't heavy enough to provide sufficent precession forces.
There are five main types of Lomcovaks. There are also variations within each type. All are performed under negative "G".