The Collaborative International Dictionary of English v.0.48:

Galoche \Ga*loche"\, Galoshe \Ga*loshe"\, [OE. galoche, galache,
   galage, shoe, F. galoche galoche, perh. altered fr. L.
   gallica a Gallic shoe, or fr. LL. calopedia wooden shoe, or
   shoe with a wooden sole, Gr. ?, dim. of ?, ?, a shoemaker's
   last; ? wood + ? foot.]
   1. A clog or patten. [Obs.]
      [1913 Webster]

            Nor were worthy [to] unbuckle his galoche.
                                                  --Chaucer.
      [1913 Webster]

   2. Hence: An overshoe worn in wet weather, especially a
      waterproof rubber overshoe extending over the ankle, worn
      over one's regular shoes; now usually written galosh. It
      is used mostly in the plural; as, it's raining, so put
      your galoshes on.
      [1913 Webster +PJC]

   3. A gaiter, or legging, covering the upper part of the shoe
      and part of the leg.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Galosh \Ga*losh"\, n.
   1. Same as Galoche, Galoshe.
      [Webster 1913 Suppl.]

   2. A strip of material, as leather, running around a shoe at
      and above the sole, as for protection or ornament.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

galosh
    n 1: a waterproof overshoe that protects shoes from water or
         snow [syn: arctic, galosh, golosh, rubber,
         gumshoe]