The Collaborative International Dictionary of English v.0.48:

Scree \Scree\ (skr[=e]), n.
   A pebble; a stone; also, a heap of stones or rocky d['e]bris.
   [Prov. Eng.] --Southey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scree
    n 1: a sloping mass of loose rocks at the base of a cliff [syn:
         talus, scree]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "scree":
   aa, abyssal rock, alluvion, alluvium, basalt, bedrock, block lava,
   brash, breccia, conglomerate, crag, debris, deposit, detritus,
   diluvium, drift, druid stone, festooned pahoehoe, gneiss, granite,
   igneous rock, lava, limestone, living rock, loess, magma,
   mantlerock, metamorphic rock, monolith, moraine, pahoehoe,
   pillow lava, porphyry, pudding stone, regolith, rock, ropy lava,
   rubble, rubblestone, sandstone, sarsen, schist, scoria, sediment,
   sedimentary rock, shelly pahoehoe, silt, sinter, stone, talus,
   tufa, tuff