The Collaborative International Dictionary of English v.0.48:

Swoop \Swoop\, n.
   A falling on and seizing, as the prey of a rapacious bird;
   the act of swooping.
   [1913 Webster]

         The eagle fell, . . . and carried away a whole litter
         of cubs at a swoop.                      --L'Estrange.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Swoop \Swoop\, v. t. [imp. & p. p. Swooped; p. pr. & vb. n.
   Swooping.] [OE. swopen, usually, to sweep, As. sw[=a]pan to
   sweep, to rush; akin to G. schweifen to rove, to ramble, to
   curve, OHG. sweifan to whirl, Icel. sveipa to sweep; also to
   AS. sw[imac]fan to move quickly. Cf. Sweep, Swift, a. &
   n., Swipe, Swivel.]
   1. To fall on at once and seize; to catch while on the wing;
      as, a hawk swoops a chicken.
      [1913 Webster]

   2. To seize; to catch up; to take with a sweep.
      [1913 Webster]

            And now at last you came to swoop it all. --Dryden.
      [1913 Webster]

            The grazing ox which swoops it [the medicinal herb]
            in with the common grass.             --Glanvill.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Swoop \Swoop\, v. i.
   1. To descend with closed wings from a height upon prey, as a
      hawk; to stoop.
      [1913 Webster]

   2. To pass with pomp; to sweep. [Obs.] --Drayton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

swoop
    n 1: (music) rapid sliding up or down the musical scale; "the
         violinist was indulgent with his swoops and slides" [syn:
         swoop, slide]
    2: a very rapid raid
    3: a swift descent through the air
    v 1: move down on as if in an attack; "The raptor swooped down
         on its prey"; "The teacher swooped down upon the new
         students" [syn: pounce, swoop]
    2: move with a sweep, or in a swooping arc
    3: seize or catch with a swooping motion [syn: swoop, swoop
       up]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "swoop":
   belly buster, belly flop, belly whopper, blow, cannonball, cascade,
   cataract, chute, collapse, come down, comedown, crash, crash dive,
   debacle, declension, declination, defluxion, descend, descending,
   descension, descent, dip down, dive, down, downbend, downcome,
   downcurve, downfall, downflow, downgrade, downpour, downrush,
   downtrend, downturn, downward trend, drop, drop down, drop off,
   dropping, fall, fall down, fall off, falling, gainer, go down,
   go downhill, gravitate, gravitation, header, inclination,
   jackknife, lose altitude, nose dive, nose-dive, parachute,
   parachute jump, pitch, plop, plummet, plummeting, plump, plunge,
   plunk, pounce, pounce on, pounce upon, pour down, power dive,
   precipitate, rain, rapids, running dive, rush, skin-dive, sky dive,
   sky-dive, sound, stationary dive, stoop, stroke, swan dive, sweep,
   swoop down, take a header, trend downward, waterfall