The Collaborative International Dictionary of English v.0.48:

Spikenard \Spike"nard\, n.[For spiked nard; cf. G. spieknarde,
   NL. spica nardi. See Spike an ear, and Nard.]
   1. (Bot.) An aromatic plant. In the United States it is the
      Aralia racemosa, often called spignet, and used as a
      medicine. The spikenard of the ancients is the
      Nardostachys Jatamansi, a native of the Himalayan
      region. From its blackish roots a perfume for the hair is
      still prepared in India.
      [1913 Webster]

   2. A fragrant essential oil, as that from the Nardostachys
      Jatamansi.
      [1913 Webster]

WordNet (r) 3.0 (2006):

spikenard
    n 1: an aromatic ointment used in antiquity [syn: nard,
         spikenard]