puerile

\PYOO-uhr-uhl; PYOOR-uhl\, adjective:Displaying or suggesting a lack of maturity; juvenile; childish

--Please, everyone, stop these puerile political rivalries, and let us attend to the slip ‘n slide.
--This is the most puerile Purell that’s ever moisturized my skin!
--Even at 5 months old, he was already acting puerile.
--Poised, puerile, and triple-parked, Paul promptly plundered the post-op room for posterity.
--All those 500-year-old men were so puerile.  She wanted a real man, like Yoda.