infantile

adjective

in·​fan·​tile ˈin-fən-ˌtī(-ə)l  -tᵊl  -ˌtēl  -(ˌ)til 

1

: of or relating to infants or infancy

2

: suitable to or characteristic of an infant

especially : very immature

infantile humor

infantility

ˌin-fən-ˈti-lə-tē 

noun

Synonyms of infantile

• childish
• immature
• adolescent
• juvenile

Examples of infantile in a Sentence

the infantile humor that teenage boys are justly famous for

Recent Examples on the Web

The incredibly painful, totally infantile, Banana Republic government shutdown ends. —Jim Cramer, CNBC, 10 Nov. 2025

The infantile form of Tay-Sachs manifests between three and six months of age, undermining gross motor control, worsening into seizures, deafness, and paralysis, and death by age five. —New Atlas, 7 Nov. 2025

But they’re born with severe brain malformations, eye abnormalities and a debilitating form of epilepsy called infantile spasms. —Erika Edwards, NBC news, 4 Oct. 2025

Muscle Man is a deeply ironic book, creating a vast chasm between Harold’s strongman self-image and his infantile powers of self-expression. —Robert Rubsam, Vulture, 18 Sep. 2025

Word History

First Known Use

1696, in the meaning defined at sense 1

Phrases Containing infantile

• infantile paralysis

Kids Definition

infantile

adjective

in·​fan·​tile ˈin-fən-ˌtīl 

-tᵊl, 

-ˌtēl

: of, relating to, or resembling infants or infancy

also : childish

Medical Definition

infantile

adjective

in·​fan·​tile ˈin-fən-ˌtīl  -tᵊl  -ˌtēl  -(ˌ)til 

1

: of, relating to, or occurring in infants or infancy

infantile eczema

2

: suitable to or characteristic of an infant

especially : very immature