Inane, stupid, or worthless as a result of immaturity; childish
Associated with or a result of childhood or youngness
Say you're in an argument with a friend over the exact definition of the word puerile (because, you know, that's the kind of thing people argue about, right?). You maintain that puerile should only be used for people who are acting childish and stupid. While your friend agrees about the childish part, she thinks "stupid" goes a little too far. According to her, puerile is used for things that are just related to young age, and that there's nothing dumb about that. "Only a poopy-head would assume that kids are stupid!" she cries at you. Frustrated and feeling that she's not understanding what you mean, you try to tell her that she's being puerile herself…but it comes out as "Well, you're a stupid-butt!" The argument continues to devolve into a volley of puerile name-calling, and nothing gets resolved.
This never would've happened if you'd checked your lexicon, which would've told you that you were both partly right, partly wrong, and fully puerile. Usually, puerile does characterize something as immaturely idiotic or silly - score for argument number one. Puerile things in this sense are often pandering and annoying; at best you roll your eyes at how overly goofy they are, and at worst their immaturity and inanity grate your patience like hard cheese. Often used to describe things like movies, jokes, and behaviors, the word implies that something simply isn't worth the attention of an adult mind. You might describe a puerile poem that's flowery and melodramatic while lacking any actual message, or a full-grown yet puerile man who pouts and whines when he's unhappy. When used negatively, puerile often helps to contrast something's actual nature with its expected maturity level, suggesting that it lacks necessary awareness, reasoning skills, or sobriety.
But to the comfort of those of us who are young at heart, the definition in argument number two is also valid. Sometimes, calling something puerile just means that it's characteristic of children or otherwise related to being young. This usage is completely neutral, not implying anything about the temperaments, natures, or intelligence levels of the things it describes. A puerile television show, then, might not be immature or moronic, but just aimed at little kids.
Example: Though I try to comport myself with dignity and maturity, I couldn't help but giggle at all the fart jokes in the puerile movie.
Example: Calling in sick from work to go see a dumb movie may seem puerile, but hey: you know you want to.
Example: The bank robbers' puerile plan rested on their assumption that the tellers would mistake their water guns for the real things.
Example: When the candidate said “He did it first!”, he invited ridicule for using a puerile excuse.
Example: Jane kept a pair of her daughter's puerile pajamas as a memento of years gone by.
Example: We could hear our young niece's puerile laughter from the next room.
You can think of puerile things as "little," in that they have "little" intelligence or maturity or are "little" like a child, right? Okay, that seems like kind of a stretch today, but it's the source of some of the word's earliest ancestors. It all started with the Proto-Indo-European root pau-, which meant "little" or "small in amount or size." This root could also be interpreted as "little in age" or "young." That sense would inspire the Latin noun puer, meaning "kid" or, specifically, "boy" (yeah, this one was influenced by patriarchy). Puer would serve as the basis for the Latin term puerilis, which meant "youthful" or "related to childhood or boyhood."
From puerilis would arise several nouns meaning "immaturity" or "childishness," including the Latin puerilitatem, the French puérilité, and, by the late 1400s, the English puerility. Many English nouns ending in -ility are simply derivatives of preexisting adjectives, but puerile is actually thought to be an adaptation of the older puerility. Puerile has been in use in English since the 1650's or 60's, although it didn't take on its now prevalent negative connotation until the 1680s.
Puerility: This noun, which means "a lack of maturity or seriousness" or "relation to youngness" is possibly the most recent English forerunner of puerile. Its plural is puerilities.
Example: Though annoyed by his puerility, Millie forced herself to laugh politely at her Uncle Al's vapid stories.
Example: The picture book's puerility made it perfect for children just starting to read.
Puerilely: This adverb form of puerile describes an action, adjective, or other adverb as characteristic of or displaying youth, immaturity, or a lack of seriousness.
Example: Millie finally lost her patience when Uncle Al puerilely asked her to pull his finger.
Example: The two third-graders were puerilely innocent of their parents' dislike for one another.
You may have already guessed this if you read the Synonyms section, but childish, immature, and juvenile all have extremely similar meanings to puerile. What makes them such good matches is that all four can describe things as either foolish or worthless to an adult temperament or as related to youth or early stages of development. Infantile can also characterize something as lacking seriousness or proper development, but it often relates specifically to babies.
From Mary Wollstonecraft's A Vindication of the Rights of Women:
Women are told from their infancy, and taught by the example of their mothers, that a little knowledge of human weakness, justly termed cunning, softness of temper, outward obedience, and a scrupulous attention to a puerile kind of propriety, will obtain for them the protection of man; and should they be beautiful, every thing else is needless, for, at least, twenty years of their lives.
According to Wollstonecraft, women in her society are unfortunately taught to be purposefully immature, to put on airs of foolishness and weakness - a puerile kind of propriety, as she puts it - to arouse the sympathies of men.
Puerile is purely foolish or childish
Puerile is Juvenile
Bring out the linguist in you! What is your own interpretation of puerile. Did you use puerile in a game? Provide an example sentence or a literary quote.