Source : Webster's Revised Unabridged Dictionary (1913)

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.

   2. A fragrant essential oil, as that from the {Nardostachys
      Jatamansi}.

Source : WordNet®

Aralia racemosa
     n : unarmed woody rhizomatous perennial plant distinguished from
         wild sarsaparilla by more aromatic roots and panicled
         umbels; southeastern North America to Mexico [syn: {American
         spikenard}, {petty morel}, {life-of-man}]