grown-up

American  

[grohn-uhp] / ˈgroʊnˈʌp /

adjective

1. having reached the age of maturity.

2. characteristic of or suitable for adults.

   grown-up behavior; grown-up fiction.

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grown-up British  

adjective

1. having reached maturity; adult

2. suitable for or characteristic of an adult

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noun

1. an adult

Other Word Forms

• grown-upness noun

Etymology

Origin of grown-up

First recorded in 1625–35; adj. use of verb phrase grow up

Example Sentences

So, faced with adult stores and mixed-age social media feeds, girls are doing what girls have always done: watching older girls, imitating grown-up rituals, reaching for whatever is available.

From The Wall Street Journal • Apr. 20, 2026

But for the admissions essay, the dry and uninspired robot voice turns one teenager after the next into only the archetype of a teenager, writing like a grown-up.

From Slate • Mar. 20, 2026

Runyon also portrayed the grown-up Cindy Brady in “A Very Brady Christmas.”

From Los Angeles Times • Mar. 9, 2026

One party source tells me existing Green voters "need reassurance we have the same values …they want to see a grown-up approach".

From BBC • Jan. 31, 2026

It’s funny I’m their aunt when they’re almost my age, but I do my best to act grown-up around them.

From "Across So Many Seas" by Ruth Behar