The Collaborative International Dictionary of English v.0.48:

Sluggish \Slug"gish\, a.
   1. Habitually idle and lazy; slothful; dull; inactive; as, a
      sluggish man.
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   2. Slow; having little motion; as, a sluggish stream.
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   3. Having no power to move one's self or itself; inert.
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            Matter, being impotent, sluggish, and inactive, hath
            no power to stir or move itself.      --Woodward.
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            And the sluggish land slumbers in utter neglect.
                                                  --Longfellow.
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   4. Characteristic of a sluggard; dull; stupid; tame; simple.
      [R.] "So sluggish a conceit." --Milton.
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   Syn: Inert; idle; lazy; slothful; indolent; dronish; slow;
        dull; drowsy; inactive. See Inert.
        [1913 Webster] -- Slug"gish*ly, adv. --
        Slug"gish*ness, n.
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WordNet (r) 3.0 (2006):

sluggishly
    adv 1: in a sluggish manner; "the smoke rose sluggishly"