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.

---

grown-up British  

adjective

1. having reached maturity; adult

2. suitable for or characteristic of an adult

---

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

Her three grown-up children - David, Caroline and Florian - also had to be told what their father had done.

From BBC • Feb. 14, 2026

And yet, for more than 75 years now, Fairyland has had a grown-up sized influence.

From Los Angeles Times • Jan. 21, 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

And Chip’s address wasn’t typed but written—in firm grown-up handwriting, like a teacher’s.

From "Found" by Margaret Peterson Haddix