A neologism ( /niːˈɒlədʒɪzəm/; from Greek νέο- (néo-), meaning "new", and λόγος (lógos), meaning "speech, utterance") is a newly coined term, word, or phrase, that may be in the process of entering common use, but has not yet been accepted into mainstream language. Neologisms are often directly attributable to a specific person, publication, period, or event. Neolexia (Greek: a "new word", or the act of creating a new word) is a fully equivalent term.
The term neologism is first attested in English in 1772, borrowed from French néologisme (1734).
In psychiatry, the term neologism is used to describe the use of words that have meaning only to the person who uses them, independent of their common meaning. This is considered normal in children, but a symptom of thought disorder (indicative of a psychotic mental illness, such as schizophrenia) in adults. People with autism also may create neologisms. Additionally, use of neologisms may be related to aphasia acquired after brain damage resulting from a stroke or head injury.