unchildlike

adjective

un·​child·​like ˌən-ˈchī(-ə)l(d)-ˌlīk 

: not resembling or appropriate to a child or childhood : not childlike

an unchildlike seriousness

… her sad, unchildlike expression …

—Louisa May Alcott

Examples of unchildlike in a Sentence

Recent Examples on the Web

The recent wave of bans comes as many Republicans, in their opposition to gun control, climate science, food stamps, public education, and other social services, work assiduously to render the lives of American children as unchildlike as possible. —Katy Waldman, The New Yorker, 10 Mar. 2023

Word History

First Known Use

circa 1775, in the meaning defined above