The Collaborative International Dictionary of English v.0.48:

Crag \Crag\ (kr[a^]g), n. [W. craig; akin to Gael. creag, Corn.
   karak, Armor. karrek.]
   1. A steep, rugged rock; a rough, broken cliff, or point of a
      rock, on a ledge.
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            From crag to crag the signal flew.    --Sir W.
                                                  Scott.
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   2. (Geol.) A partially compacted bed of gravel mixed with
      shells, of the Tertiary age.
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The Collaborative International Dictionary of English v.0.48:

Crag \Crag\, n. [A form of craw: cf. D. kraag neck, collar, G.
   kragen. See Craw.]
   1. The neck or throat [Obs.]
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            And bear the crag so stiff and so state. --Spenser.
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   2. The neck piece or scrag of mutton. --Johnson.
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WordNet (r) 3.0 (2006):

crag
    n 1: a steep rugged rock or cliff