The Collaborative International Dictionary of English v.0.48:

Childlike \Child"like`\ (ch[imac]ld"l[imac]k`), a.
   Resembling a child, or that which belongs to children;
   becoming a child; meek; submissive; dutiful. "Childlike
   obedience." --Hooker.
   [1913 Webster]

   Note: Childlike, as applied to persons grown up, is commonly
         in a good sense; as, childlike grace or simplicity;
         childlike modesty.
         [1913 Webster]

WordNet (r) 3.0 (2006):

childlike
    adj 1: befitting a young child; "childlike charm" [syn:
           childlike, childly]
    2: exhibiting childlike simplicity and credulity; "childlike
       trust"; "dewy-eyed innocence"; "listened in round-eyed
       wonder" [syn: childlike, wide-eyed, round-eyed, dewy-
       eyed, simple]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "childlike":
   angelic, artless, babish, babyish, beardless, blameless, bluff,
   blunt, born yesterday, boyish, boylike, calflike, candid, childish,
   clear, coltish, confiding, credulous, decrepit, dependent,
   depending, direct, doddering, doddery, doited, doting, dovelike,
   faultless, frank, girlish, girllike, guileless, guiltless,
   immature, in the clear, incorrupt, infantile, infantine, ingenu,
   ingenuous, innocent, kiddish, lamblike, maiden, maidenly, naive,
   not guilty, offenseless, open, openhearted, outspoken, plain,
   prelapsarian, pristine, puerile, puplike, puppyish, puppylike,
   reliant, relying, reproachless, sans reproche, senile, simple,
   simplehearted, simpleminded, sincere, single-hearted,
   single-minded, sinless, trustful, trusting, trusty, unassuming,
   uncorrupted, undefiled, undissembling, unfallen, unguarded,
   unlapsed, unreserved, unsophisticated, unsuspecting, unsuspicious,
   untouched by evil, unwary, with clean hands, without reproach,
   without suspicion, young, youthful