The Collaborative International Dictionary of English v.0.48:

Ungentle \Un*gen"tle\, a.
   Not gentle; lacking good breeding or delicacy; harsh.
   [1913 Webster]

         Vicious, ungentle, foolish, blunt, unkind. --Shak.
   [1913 Webster]

         That ungentle flavor which distinguishes nearly all our
         native and uncultivated grapes.          --Hawthorne.
   [1913 Webster] -- Un*gen"tle*ness, n. -- Un*gen"tly, adv.
   [1913 Webster]