The Collaborative International Dictionary of English v.0.48:

Sassafras \Sas"sa*fras\, n. [F. sassafras (cf. It. sassafrasso,
   sassafras, Sp. sasafras, salsafras, salsifrax, salsifragia,
   saxifragia), fr. L. saxifraga saxifrage. See Saxifrage.]
   (Bot.)
   An American tree of the Laurel family (Sassafras
   officinale); also, the bark of the roots, which has an
   aromatic smell and taste.
   [1913 Webster]

   Australian sassafras, a lofty tree (Doryophora Sassafras)
      with aromatic bark and leaves.

   Chilian sassafras, an aromatic tree (Laurelia
      sempervirens).

   New Zealand sassafras, a similar tree (Laurelia Novae
      Zelandiae).

   Sassafras nut. See Pichurim bean.

   Swamp sassafras, the sweet bay (Magnolia glauca). See
      Magnolia.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sassafras
    n 1: yellowwood tree with brittle wood and aromatic leaves and
         bark; source of sassafras oil; widely distributed in
         eastern North America [syn: sassafras, sassafras tree,
         Sassafras albidum]
    2: dried root bark of the sassafras tree