childish
Translation
childish, immature
Examples
His behaviour was very childish.
His behavior was very childish.
Don't be so childish!
Don't be so childish!
Grammar Patterns
((adj.)) behaving badly in a way that would be expected of a child. His childish jokes annoyed everyone.
Similar Words
Synonyms: immature, juvenile, puerile; Antonyms: mature, adult. Note the difference with 'childlike', which is often positive.
Etymology
From 'child' + the suffix '-ish', meaning 'like' or 'typical of'.
Memory Tips
The '-ish' suffix often has a negative connotation (e.g., selfish). Think of an adult behaving like a badly-behaved child.