The simple definition of "pitch" is where the nose of the aircraft is pointed in relation to the horizon.
So, the term "pitch down," would mean to lower the nose in relation to the horizon.
The term "pitch up," would mean to raise the nose in relation to the horizon.
Pitch is controlled by the elevators (in an airplane, anyway - helicopters are a different story) which are adjusted by either pushing forward, or pulling back on the stick/yoke.
Sorry, it has nothing to do with the distance to the seat in front of you.
Jack @ AUS