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]

Moby Thesaurus II by Grady Ward, 1.0:

140 Moby Thesaurus words for "takeoff":
   A, alpha, anabasis, ascension, ascent, base, basis, beginning,
   blast-off, boarding, booster rocket, burlesque, caricature,
   catapult, clamber, climb, climbing, commencement, copying,
   counterfeiting, creation, cutting edge, dawn, edge, elevation,
   embarkation, embarkment, emplanement, emulation, enplanement,
   entrainment, escalade, establishment, fakery, farce, flying start,
   following, forgery, foundation, fountain, fresh start, ground loop,
   gush, gyring up, hit-off, hopoff, imitation, impersonation,
   imposture, impression, increase, institution, jet, jump, jump-off,
   kick-off, lampoon, leading edge, leap, levitation,
   line of departure, mimesis, mirroring, mockery, mount, mounting,
   new departure, oncoming, onomatopoeia, onset, opening, origin,
   origination, outbreak, outset, outsetting, outstart, parody,
   pastiche, plagiarism, plagiary, point of departure,
   port of embarkation, repetition, rise, rising, rocketing up,
   rotation, running start, saltation, satire, send-off, setoff,
   setout, setting in motion, setting-up, shooting up, simulation,
   soaring, spout, spring, spurt, square one, squib, start, start-off,
   starting, starting gate, starting place, starting point,
   starting post, surge, take-off, taking off, travesty, upclimb,
   upcoming, updraft, upgang, upgo, upgoing, upgrade, upgrowth,
   uphill, upleap, uplift, upping, uprisal, uprise, uprising, uprush,
   upshoot, upslope, upsurge, upsurgence, upsweep, upswing, vault,
   wicked imitation, zooming