The Collaborative International Dictionary of English v.0.48:

Takeoff \Take"off`\, Take-off \Take"-off`\, n.
   1. An imitation, especially in the way of caricature; -- used
      with of or on; as, the comedian did a hilarious takeoff on
      the president.
      [1913 Webster +PJC]

   2. The spot at which one takes off; specif., the place from
      which a jumper rises in leaping.
      [Webster 1913 Suppl.]

            The take-off should be selected with great care, and
            a pit of large dimensions provided on the landing
            side.                                 --Encyc. of
                                                  Sport.
      [Webster 1913 Suppl.]

   3. The beginning of a leap from a surface or a flight into
      the air, especially the process or event of an airplane
      leaving the ground and beginning its flight; as, the
      takeoff of flight CA123 was scheduled for 3:00 PM.
      [PJC]

WordNet (r) 3.0 (2006):

takeoff
    n 1: a departure; especially of airplanes
    2: the initial ascent of an airplane as it becomes airborne
    3: a composition that imitates or misrepresents somebody's
       style, usually in a humorous way [syn: parody, lampoon,
       spoof, sendup, mockery, takeoff, burlesque,
       travesty, charade, pasquinade, put-on]
    4: humorous or satirical mimicry [syn: parody, mockery,
       takeoff]