The Collaborative International Dictionary of English v.0.48:

Gallop \Gal"lop\, v. i. [imp. & p. p. Galloped; p. pr. & vb.
   n. Galloping.] [OE. galopen, F. galoper, of German origin;
   cf. assumed Goth. ga-hlaupan to run, OHG. giloufen, AS.
   gehle['a]pan to leap, dance, fr. root of E. leap, and a
   prefix; or cf. OFlem. walop a gallop. See Leap, and cf. 1st
   Wallop.]
   1. To move or run in the mode called a gallop; as a horse; to
      go at a gallop; to run or move with speed.
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            But gallop lively down the western hill. --Donne.
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   2. To ride a horse at a gallop.
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   3. Fig.: To go rapidly or carelessly, as in making a hasty
      examination.
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            Such superficial ideas he may collect in galloping
            over it.                              --Locke.
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The Collaborative International Dictionary of English v.0.48:

Galloping \Gal"lop*ing\, a.
   Going at a gallop; progressing rapidly; as, a galloping
   horse.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "galloping":
   agile, breakneck, dashing, double-quick, eagle-winged, expeditious,
   express, fast, fleet, flying, hair-trigger, hasty, headlong,
   hustling, light of heel, light-footed, lively, mercurial, nimble,
   nimble-footed, precipitate, prompt, quick, quick as lightning,
   quick as thought, rapid, reckless, running, snappy, spanking,
   speedy, swift, winged