the economic transactions presented as the machinations rapacious traders are not merely puerile [...] they are also unintelligible by the criteria of even the most primitive economic logic

charged with American puerility

The whole notion of coolness was puerile.

not exaggerated or solipsistic or puerile or sentimental or solecistic

But he’s never amounted to much, he remains puerile and full of complaints, in spite of his middle-aged man’s body.