Pitch
From Kerbal Space Program Wiki
Pitch
The Pitch axis is one of the three principal axes in which an aircraft or spacecraft can change orientation. A shift in the pitch axis will cause a craft's nose to move up or down, with the tail moving in the opposite direction.
Larger aircraft/spacecraft, especially long launch vehicles, will have very little Pitch control without the addition of control parts.
Placing RCS thruster blocks or movable control surfaces on the nose and tail will increase a craft's Pitch ability. Engines with thrust vectoring will help with Pitch control.
