in·fan·tile /ˈɪnfənˌtaɪl, tḷ, ˌtil, (ˌ)tɪl/
  (a.)嬰兒的,幼稚的,初期的
  In·fan·tile a.  Of or pertaining to infancy, or to an infant; similar to, or characteristic of, an infant; childish; as, infantile behavior.
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  infantile
       adj 1: indicating a lack of maturity; "childish tantrums";
              "infantile behavior" [syn: childish]
       2: of or relating to infants or infancy; "infantile paralysis"
       3: being or befitting or characteristic of an infant;
          "infantile games"