The Collaborative International Dictionary of English v.0.48:

Linseed \Lin"seed`\ (l[i^]n"s[=e]d`), n. [OE. lin flax + seed.
   See Linen.] (Bot.)
   The seeds of flax, from which linseed oil is obtained.
   [Written also lintseed.]
   [1913 Webster]

   Linseed cake, the solid mass or cake which remains when oil
      is expressed from flaxseed.

   Linseed meal, linseed cake reduced to powder.

   Linseed oil, oil obtained by pressure from flaxseed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

linseed
    n 1: the seed of flax used as a source of oil [syn: linseed,
         flaxseed]