more infantile

The theory that regression can spotlight personality disorders found in more infantile states is also widely held.

Never did a people of advanced culture have a more infantile religion.

And yet has it not something more naive, more infantile, than most modern trifles of that sort?

She told no more infantile perilous tales about husbands who ate peas with a knife.

It makes her complexion more infantile, her hair more golden, and her eyes larger.