The Collaborative International Dictionary of English v.0.48:

Spectroscope \Spec"tro*scope\, n. [Spectrum + -scope.] (Physics)
   An optical instrument for forming and examining spectra (as
   that of solar light, or those produced by flames in which
   different substances are volatilized), so as to determine,
   from the position of the spectral lines, the composition of
   the substance.
   [1913 Webster] Spectroscopic

WordNet (r) 3.0 (2006):

spectroscope
    n 1: an optical instrument for spectrographic analysis [syn:
         spectroscope, prism spectroscope]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "spectroscope":
   Cassegrainian telescope, Newtonian telescope, OAO, OSO,
   astronomical observatory, astronomical telescope, chromatoscope,
   coelostat, coronagraph, coronograph, heliostat, kaleidoscope,
   observatory, orrery, oscilloscope, periscope, planetarium,
   radar telescope, radio observatory, radio telescope, reflector,
   refractor, spectrograph, spectroheliograph, spectrohelioscope,
   stereoscope, telescope