The Collaborative International Dictionary of English v.0.48:

Swim \Swim\, v. i. [imp. Swamor Swum; p. p. Swum; p. pr. &
   vb. n. Swimming.] [AS. swimman; akin to D. zwemmen, OHG.
   swimman, G. schwimmen, Icel. svimma, Dan. sw["o]mme, Sw.
   simma. Cf. Sound an air bladder, a strait.]
   1. To be supported by water or other fluid; not to sink; to
      float; as, any substance will swim, whose specific gravity
      is less than that of the fluid in which it is immersed.
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   2. To move progressively in water by means of strokes with
      the hands and feet, or the fins or the tail.
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            Leap in with me into this angry flood,
            And swim to yonder point.             --Shak.
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   3. To be overflowed or drenched. --Ps. vi. 6.
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            Sudden the ditches swell, the meadows swim.
                                                  --Thomson.
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   4. Fig.: To be as if borne or floating in a fluid.
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            [They] now swim in joy.               --Milton.
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   5. To be filled with swimming animals. [Obs.]
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            [Streams] that swim full of small fishes. --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Swim \Swim\, v. i. [OE. swime dizziness, vertigo, AS.
   sw[imac]ma; akin to D. zwijm, Icel. svimi dizziness, svina to
   subside, sv[imac]a to abate, G. schwindel dizziness,
   schwinden to disappear, to dwindle, OHG. sw[imac]nan to
   dwindle. Cf. Squemish, Swindler.]
   To be dizzy; to have an unsteady or reeling sensation; as,
   the head swims.
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The Collaborative International Dictionary of English v.0.48:

Swim \Swim\, v. t.
   1. To pass or move over or on by swimming; as, to swim a
      stream.
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            Sometimes he thought to swim the stormy main.
                                                  --Dryden.
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   2. To cause or compel to swim; to make to float; as, to swim
      a horse across a river.
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   3. To immerse in water that the lighter parts may float; as,
      to swim wheat in order to select seed.
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The Collaborative International Dictionary of English v.0.48:

Swim \Swim\, n.
   1. The act of swimming; a gliding motion, like that of one
      swimming. --B. Jonson.
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   2. The sound, or air bladder, of a fish.
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   3. A part of a stream much frequented by fish. [Eng.]
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   Swim bladder, an air bladder of a fish.

   To be in the swim, to be in a favored position; to be
      associated with others in active affairs. [Colloq.]
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WordNet (r) 3.0 (2006):

swim
    n 1: the act of swimming; "it was the swimming they enjoyed
         most": "they took a short swim in the pool" [syn:
         swimming, swim]
    v 1: travel through water; "We had to swim for 20 minutes to
         reach the shore"; "a big fish was swimming in the tank"
    2: be afloat either on or below a liquid surface and not sink to
       the bottom [syn: float, swim] [ant: go down, go
       under, settle, sink]
    3: be dizzy or giddy; "my brain is swimming after the bottle of
       champagne"
    4: be covered with or submerged in a liquid; "the meat was
       swimming in a fatty gravy" [syn: swim, drown]
    5: move as if gliding through water; "this snake swims through
       the soil where it lives"