childlike

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Like or befitting a child, as in innocence, trustfulness, or candor.

from The Century Dictionary.

• Resembling a child or that which is proper to childhood; becoming to or characteristic of a child; hence, submissive, dutiful, trustful, artless, inexperienced, etc.
• Synonyms Childlike, Childish, Infantile, Infantine. Childlike and childish express that which is characteristic of a child, the former applying to that which is worthy of approbation, or at least does not merit disapproval, and the latter usually to that which is not: as, a childlike freedom from guile; a childish petulance. To express that which belongs to the period of childhood, without qualifying it as good or bad, child or childhood is often used in composition: as, child-toil, childhood-days. Infantile and infantine are applied to the first stages of childhood; no clear distinction between them has yet been established. See youthful.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Resembling a child, or that which belongs to children; becoming a child; meek; submissive; dutiful.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective innocent and trustful; credulous; artless
• adjective of, like, or suitable for a child; meek; submissive

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective exhibiting childlike simplicity and credulity
• adjective befitting a young child