immature

The word “immature” means behaving in a childish or emotionally undeveloped way. In plain terms, not fully grown up — either physically undeveloped, or acting in a childish way for one's age.

“Immature” is pronounced ih-muh-TYOOR (/ɪməˈtjʊə(ɹ)/ in IPA).

Here is “immature” used in a sentence: “His immature jokes annoyed the rest of the office.”

“Immature” is an adjective.

The word “immature” comes from Latin. From Latin immaturus, formed from "im-" ("not") plus maturus ("ripe").

“Immature” is an uncommon word in modern English.

“Immature” has 2 distinct senses listed in this dictionary. The most common is: behaving in a childish or emotionally undeveloped way.

When describing behavior, immature means acting in a childish or emotionally undeveloped way despite one's actual age, such as an adult throwing a tantrum. When describing growth or development, immature means not yet fully grown, as in an immature plant or an immature stage of an organism, with no judgment about behavior involved.

Immature is the broader term, covering both a lack of physical or biological development and a lack of emotional maturity in behavior. Childish specifically criticizes behavior as being like that of a child, and is generally used only in the behavioral sense, not to describe physical growth.

Not always. When applied to behavior, it is typically critical, implying someone should know better. But when used to describe biological or developmental stages, such as an immature cell or an immature ecosystem, it is a neutral, technical description rather than an insult.