childish

US /ˈtʃaɪl.dɪʃ/
UK /ˈtʃaɪl.dɪʃ/
"childish" picture
1.

enfantin, puéril

of, like, or appropriate to a child

:
She has a very childish handwriting.
Elle a une écriture très enfantine.
His behavior was quite childish for his age.
Son comportement était assez enfantin pour son âge.