adjective

infantile

IN-fuhn-tyle/ˈɪnfəntaɪl/

Characteristic of a very young child.

The adult's infantile tantrum includes kicking on the floor after losing the game.

A young adult throws a visibly childish tantrum after losing a board game, while her older opponent remains seated.

Etymology

inLatinnot

+fantLatinto speak

+ileLatinpertaining to

The 'not speaking' base had become a word for a young child. Infantile first meant pertaining to infants, then also infant-like—the connection behind its use for childish immaturity.

In context

DoctorRamani3:16

emotional immaturity is lots of things and unlike narcissism it's not always as well defined it's used conversationally emotional immaturity is takes in territory like adolescence selfishness infantile Tantrums

Narcissist or emotionally immature? (The difference really matters)

More examples

She finds their infantile jokes more annoying than funny.
The doctor checks for infantile reflexes during the exam.
Blaming everyone else is an infantile response to criticism.

Forms

infantile

infant noun — A baby or very young child.

infancy noun — The earliest stage of a child's life.

Similar words

childish: Suggests behavior typical of children, not specifically babies.
immature: Emphasizes insufficient development or judgment rather than resemblance to babies.