The Collaborative International Dictionary of English v.0.48:

lasagna \lasagna\, lasagne \lasagne\(l[.a]*z[.a]n"y[u^]), n.
   1. A baked dish of layers of lasagna[2] pasta with sauce and
      cheese and meat or vegetables; -- a popular dish of
      Italian cuisine.
      [WordNet 1.5]

   2. large flat rectangular strips of pasta.
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

lasagna
    n 1: baked dish of layers of lasagna pasta with sauce and cheese
         and meat or vegetables [syn: lasagna, lasagne]
    2: very wide flat strips of pasta [syn: lasagna, lasagne]