The Collaborative International Dictionary of English v.0.48:

Spectrometer \Spec*trom"e*ter\, n. [Spectrum + -meter.]
   (Physics)
   A spectroscope fitted for measurements of the luminious
   spectra observed with it.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spectrometer
    n 1: spectroscope for obtaining a mass spectrum by deflecting
         ions into a thin slit and measuring the ion current with an
         electrometer [syn: mass spectrometer, spectrometer]