Source : Webster's Revised Unabridged Dictionary (1913)

Thematic \The*mat"ic\, a. [Gr. ?: cf. F. th['e]matique.]
   1. (Gram.) Of or pertaining to the theme of a word. See
      {Theme}, n., 4.

   2. (Mus.) Of or pertaining to a theme, or subject.

   {Thematic catalogue} (Mus.), a catalogue of musical works
      which, besides the title and other particulars, gives in
      notes the theme, or first few measures, of the whole work
      or of its several movements.

Source : WordNet®

thematic
     adj 1: relating to or constituting a topic of discourse
     2: of or relating to a melodic subject [ant: {unthematic}]