infantile

[ in-fuhn-tahyl, -til ]

adjective

1. characteristic of or befitting an infant; babyish; childish:

   infantile behavior.

   Synonyms: weak, immature, puerile

   Antonyms: mature, adult

2. of or relating to infants or infancy:

   infantile diseases.

3. Physical Geography. youthful ( def 5 ).

infantile

/ ˌɪnfənˈtɪlɪtɪ; ˈɪnfənˌtaɪl /

adjective

1. like a child in action or behaviour; childishly immature; puerile
2. of, relating to, or characteristic of infants or infancy
3. in an early stage of development

Derived Forms

• infantility, noun

Other Words From

• in·fan·til·i·ty [in-f, uh, n-, til, -i-tee], noun

Word History and Origins

Origin of infantile¹

From the Latin word infantīlis, dating back to 1690–1700. See infant, -ile

Synonym Study

See childish.

Example Sentences

In fact, most people can’t remember events from the first few years of their lives—a phenomenon researchers have dubbed infantile amnesia.

From Singularity Hub 

I think it’s partly because the audience for a lot of that stuff is kids – and the culture in general is a bit infantile in this era.

From Washington Blade

The idea that we can enjoy the benefits of society while owing nothing in return is literally infantile.

From The Daily Beast

The United States got an F — and soon 550,000 dead — because the ignorant or infantile among us, wanting what they wanted when they wanted it, defeated the nation’s adults.

From Washington Post

The seeds of future nightmares may be planted early in life, during what’s known as the “infantile amnesia” period, which lasts from birth to about age three and a half, and is a time of life during which virtually no enduring memories are formed.

From Time

At one point, Valle offered an apology to anybody who had been “hurt, shocked or offended by my infantile actions.”

From The Daily Beast

It was sweet and funny and self-deprecating, nothing like the infantile behavior she had just displayed.

From The Daily Beast

It's how we project our own catastrophe of infantile adulthood.

From The Daily Beast

He led her by the hand, and confided to her infantile spirit all his thoughts, his illusions, his day-dreams.

From Project Gutenberg

The Scherzo is neither good nor bad; the trio is so innocent that it would be almost too infantile for a Sniegourotchka.

From Project Gutenberg

He listened and heard soft breathing that stopped just short of being an infantile snore.

From Project Gutenberg

She was apparently about six years of age, and the picture of infantile innocence and loveliness.

From Project Gutenberg

In respect of one symptom or several, many individuals may remain throughout life in an infantile condition.

From Project Gutenberg

Related Words

• childish
• sophomoric