The Collaborative International Dictionary of English v.0.48:

Tickle \Tic"kle\, v. t. [imp. & p. p. Tickled; p. pr. & vb. n.
   Tickling.] [Perhaps freq. of tick to beat; pat; but cf.
   also AS. citelian to tickle, D. kittelen, G. kitzlen, OHG.
   chizzil[=o]n, chuzzil[=o]n, Icel. kitla. Cf. Kittle, v. t.]
   1. To touch lightly, so as to produce a peculiar thrilling
      sensation, which commonly causes laughter, and a kind of
      spasm which become dangerous if too long protracted.
      [1913 Webster]

            If you tickle us, do we not laugh?    --Shak.
      [1913 Webster]

   2. To please; to gratify; to make joyous.
      [1913 Webster]

            Pleased with a rattle, tickled with a straw. --Pope.
      [1913 Webster]

            Such a nature
            Tickled with good success, disdains the shadow
            Which he treads on at noon.           --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tickling
    adj 1: exciting by touching lightly so as to cause laughter or
           twitching movements [syn: tickling, tingling,
           titillating]
    n 1: the act of tickling [syn: tickle, tickling,
         titillation]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "tickling":
   alluring, appealing, appetizing, attractive, beguiling, bewitching,
   blandishing, cajoling, captivating, catching, charismatic,
   charming, coaxing, come-hither, coquettish, enchanting, engaging,
   enravishing, enthralling, enticing, entrancing, exciting, exotic,
   fascinating, fetching, flirtatious, glamorous, hypnotic,
   interesting, intriguing, inviting, irresistible, juicy, lively,
   mesmeric, mouth-watering, piquant, pleasant stimulation,
   prepossessing, provocative, provoking, provoquant, racy, ravishing,
   readable, rich, seducing, seductive, siren, sirenic, spellbinding,
   spellful, spicy, stimulating, succulent, taking, tantalizing,
   teasing, tempting, thought-challenging, thought-inspiring,
   thought-provoking, tickle, tickliness, ticklish, ticklishness,
   tickly, titillating, titillation, titillative, winning, winsome,
   witching