juvenile

If you're being juvenile, you're not acting your age. Unless of course you are a juvenile. In which case, carry on.

While the noun juvenile refers to someone not physically or emotionally mature, the word is often used as an adjective to refer to anything specifically for young people, such as juvenile reading materials or movies. It can be derisive, as in "Don't act so juvenile," suggesting a silliness unbecoming an adult. The word comes from the Latin juvenīlis, meaning "youthful" — similar, but much more flattering.

Definitions of juvenile
  1. adjective
    of or relating to or characteristic of or appropriate for children or young people
    juvenile diabetes”
    juvenile fashions”
  2. adjective
    displaying or suggesting a lack of maturity
    “their behavior was juvenile
    synonyms: adolescent, jejune, puerile, sophomoric
    immature
    characteristic of a lack of maturity
  3. noun
    a young person, not fully developed
    synonyms: juvenile person
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    Antonyms:
    adult, grownup
    a fully developed person from maturity onward
    types:
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    preteen, preteenager
    a preadolescent boy or girl (usually between 9 and 12 years of age)
    adolescent, stripling, teen, teenager
    a juvenile between the onset of puberty and maturity
    child, fry, kid, minor, nestling, nipper, shaver, small fry, tiddler, tike, tyke, youngster
    a young person of either sex
    ingenue
    an artless innocent young girl (especially as portrayed on the stage)
    spring chicken, young person, younker, youth
    a young person (especially a young man or boy)
    bairn
    a child: son or daughter
    blade
    a dashing young man
    buster
    a robust child
    changeling
    a child secretly exchanged for another in infancy
    chebab
    a Palestinian juvenile 10-15 years old who fights against the Israelis
    child prodigy, infant prodigy, wonder child
    a prodigy whose talents are recognized at an early age
    foster child, foster-child, fosterling
    a child who is raised by foster parents
    hobbledehoy
    an awkward bad-mannered adolescent boy
    imp, monkey, rapscallion, rascal, scalawag, scallywag, scamp
    one who is playfully mischievous
    kiddy
    a young child
    mod
    a British teenager or young adult in the 1960s; noted for their clothes consciousness and opposition to the rockers
    orphan
    a child who has lost both parents
    pachuco
    a Mexican-American teenager who belongs to a neighborhood gang and who dresses in showy clothes
    peanut
    a young child who is small for his age
    poster child
    a child afflicted by some disease or deformity whose picture is used on posters to raise money for charitable purposes
    kindergartener, kindergartner, preschooler
    a child who attends a preschool or kindergarten
    punk, punk rocker
    a teenager or young adult who is a performer (or enthusiast) of punk rock and a member of the punk youth subculture
    pup, puppy
    an inexperienced young person
    rocker
    a teenager or young adult in the 1960s who wore leather jackets and rode motorcycles
    pupil, school-age child, schoolchild
    a young person attending school (up through senior high school)
    silly
    a word used for misbehaving children
    slip
    a young and slender person
    sprog
    a child
    bambino, toddler, tot, yearling
    a young child
    urchin
    a poor and often mischievous city child
    street child, waif
    a homeless child especially one forsaken or orphaned
    young buck, young man
    a teenager or a young adult male
    type of:
    individual, mortal, person, somebody, someone, soul
    a human being
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