Source : Webster's Revised Unabridged Dictionary (1913)

Unbridled \Un*bri"dled\, a. [Pref. un- not + bridled.]
   Loosed from the bridle, or as from the bridle; hence,
   unrestrained; licentious; violent; as, unbridled passions.
   ``Unbridled boldness.'' --B. Jonson.

         Lands deluged by unbridled floods.       --Wordsworth.
   -- {Un*bri"dled*ness}, n. --Abp. Leighton.