Child"ish, a.
1.
Of, pertaining to, befitting, or resembling, a child.
"
Childish innocence."
Macaulay.
2.
Puerile; trifling; weak.
Methinks that simplicity in her countenance is rather childish than innocent.
Addison.
⇒ Childish, as applied to persons who are grown up, is in a disparaging sense; as, a childish temper.
© Webster 1913.