Antonyms for more infantile

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Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.

EXAMPLES FROM THE WEB FOR MORE INFANTILE

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.

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

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