Source : Webster's Revised Unabridged Dictionary (1913)

Thorny \Thorn"y\, a. [Compar. {Thornier}; superl. {Thorniest}.]
   [Cf. AS. [thorn]orniht.]
   1. Full of thorns or spines; rough with thorns; spiny; as, a
      thorny wood; a thorny tree; a thorny crown.

   2. Like a thorn or thorns; hence, figuratively, troublesome;
      vexatious; harassing; perplexing. ``The thorny point of
      bare distress.'' --Shak.

            The steep and thorny way to heaven.   --Shak.

   {Thorny rest-harrow} (Bot.), rest-harrow.

   {Thorny trefoil}, a prickly plant of the genus {Fagonia} ({F.
      Cretica}, etc.).

Source : WordNet®

thorny
     adj 1: bristling with perplexities; "the thorny question of states'
            rights"
     2: having or covered with protective barbs or quills or spines
        or thorns or setae etc.; "a horse with a short bristly
        mane"; "bristly shrubs"; "burred fruits"; "setaceous
        whiskers" [syn: {barbed}, {barbellate}, {briary}, {briery},
         {bristled}, {bristly}, {burred}, {burry}, {prickly}, {setose},
         {setaceous}, {spiny}]
     [also: {thorniest}, {thornier}]

thornier
     See {thorny}