The Collaborative International Dictionary of English v.0.48:

kittenish \kit"ten*ish\, a.
   Resembling a kitten; playful; as, a kittenish disposition.
   --Richardson.
   [1913 Webster] -- kit"ten*ish*ly, adv. --
   kit"ten*ish*ness, n.
   [PJC]

WordNet (r) 3.0 (2006):

kittenish
    adj 1: playful like a lively kitten [syn: kittenish, frisky]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "kittenish":
   babish, baby, babyish, catlike, cattish, catty, coltish,
   coquettish, coy, distaff, doll-like, dollish, elvish, felid,
   feline, female, feminine, flirtatious, frisky, frolicsome,
   gentlewomanlike, girlish, gynecic, gynecoid, gynic, impish,
   in arms, in diapers, in nappies, in swaddling clothes,
   in the cradle, infant, infantile, infantine, ladylike, larkish,
   leonine, lionlike, little-girlish, maidenly, matronal, matronlike,
   matronly, mischievous, muliebral, neonatal, newborn, petticoat,
   playful, prankish, roguish, seductive, sportive, tigerish,
   womanish, womanlike, womanly