Terms And Definitions - Takeoffs And Departure Climbs

Although the takeoff and climb is one continuous
maneuver, it will be divided into three separate steps
for purposes of explanation: (1) the takeoff roll, (2) the
lift-off, and (3) the initial climb after becoming airborne.

• 
  Takeoff Roll (ground roll)—the portion of the
  takeoff procedure during which the airplane is
  accelerated from a standstill to an airspeed that
  provides sufficient lift for it to become airborne.
  
• 
  Lift-off (rotation)—the act of becoming airborne as a result of the wings lifting the airplane
  off the ground or the pilot rotating the nose up,
  increasing the angle of attack to start a climb.
  
• 
  Initial Climb—begins when the airplane leaves
  the ground and a pitch attitude has been established to climb away from the takeoff area.
  Normally, it is considered complete when the
  plane has reached a safe maneuvering altitude,
  or an en route climb has been established.