The Collaborative International Dictionary of English v.0.48:

Snowdrift \Snow"drift`\, n.
   A bank of drifted snow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

snowdrift
    n 1: a mass of snow heaped up by the wind

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "snowdrift":
   anthill, avalanche, bank, blizzard, cock, crystal, drift,
   driven snow, dune, embankment, flake, flurry, granular snow,
   haycock, haymow, hayrick, haystack, heap, hill, igloo,
   mantle of snow, mogul, molehill, mound, mow, pile, pyramid, rick,
   slosh, slush, snow, snow banner, snow bed, snow blanket,
   snow blast, snow fence, snow flurry, snow roller, snow slush,
   snow squall, snow wreath, snow-crystal, snowball, snowbank,
   snowbridge, snowcap, snowfall, snowfield, snowflake, snowland,
   snowman, snowscape, snowshed, snowslide, snowslip, snowstorm,
   stack, wet snow