The Collaborative International Dictionary of English v.0.48:

Spectroscopy \Spec*tros"co*py\, n.
   the art and science dealing with the use of a spectroscope,
   and the production and analysis of spectra; the action of
   using a spectroscope.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

spectroscopy
    n 1: the use of spectroscopes to analyze spectra [syn:
         spectroscopy, spectrometry, spectroscopic analysis,
         spectrum analysis, spectrographic analysis]