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

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

I mean, he’s a proper grown-up and he’s humble and so gifted and had such an amazing career.

From Los Angeles Times • Jan. 22, 2026

So I set out to create it: a blueberry muffin with a seasonally appropriate soul — deeper, darker, more fragrant, a little more grown-up.

From Salon • Dec. 16, 2025

Her grown-up children, who she hadn't seen in two years, were in Oslo to greet her.

From BBC • Dec. 12, 2025

“I’m glad you came, I was afraid you wouldn’t.” she said, with her most grown-up air.

From "Little Women" by Louisa May Alcott