When describing a child who is innocent or lacks experience, the common phrase is a "naive child". However, there are many other synonyms that can be used to describe a child with similar qualities. For example, "innocent child" may be a more positive alternative that implies purity or lack of wrongdoing. "Unworldly child" suggests a lack of understanding of the complexities of society, while "childlike" emphasizes their youthful, carefree nature. "Ingenuous child" implies a lack of pretense or deceit, and "unsophisticated child" suggests a lack of worldly knowledge or experience. Ultimately, the chosen synonym depends on the tone and context of the writing, but all highlight the child's naivete in a distinct way.