Wiktionary
a. Not childlike; inappropriate for a child to do or be
Usage examples of "unchildlike".
And then, before he could say anything, the unchildlike child proceeded to tell him about his own program.
Her very unchildlike perfume reached him across the table, filling his head.
Later he saw the girl again, in a corner with the youngster who had wanted to be married that season, kissing with what seemed to be unchildlike passion.
I looked at her in silence and wondered what had brought the unchildlike expression of sadness to her face which I now observed for the first time there.
Veraguth was struck by the grave, unchildlike quality of that glance and that awakening.
But between her and David a friendship had sprung up, a strange, unchildlike but good friendship.
Luken sighed, eyes on the child who went so solemn and unchildlike ahead of them.
Quite her sad, unchildlike expression, and thin little face, with the big dark eyes.
Magda made no answer, but she stood looking at him with an odd, unchildlike deviltry in her sombre eyes.
A most unchildlike child, Alberich reflected later, as he left the boy to finish his feast.
Vanyel found his own voice sounding incredibly calm considering the pain of past memories, and the ache for this unchildlike child.