The Collaborative International Dictionary of English v.0.48:

Ticklish \Tic"klish\, a.
   1. Sensible to slight touches; easily tickled; as, the sole
      of the foot is very ticklish; the hardened palm of the
      hand is not ticklish. --Bacon.
      [1913 Webster]

   2. Standing so as to be liable to totter and fall at the
      slightest touch; unfixed; easily affected; unstable.
      [1913 Webster]

            Can any man with comfort lodge in a condition so
            dismally ticklish?                    --Barrow.
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   3. Difficult; nice; critical; as, a ticklish business.
      [1913 Webster]

            Surely princes had need, in tender matters and
            ticklish times, to beware what they say. --Bacon.
      [1913 Webster] -- Tic"klish*ly, adv. --
      Tic"klish*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ticklish
    adj 1: difficult to handle; requiring great tact; "delicate
           negotiations with the big powers";"hesitates to be
           explicit on so ticklish a matter"; "a touchy subject"
           [syn: delicate, ticklish, touchy]