A neologism () (from Greek νέο- néo(="new") and λόγος /lógos, meaning "speech, utterance") is a relatively recent or isolated term, word, or phrase that may be in the process of entering common use, but that has not been fully accepted into mainstream language. Neologisms are often driven by changes in culture and technology. In the process of language formation, neologisms are more mature than protologisms. A word whose development stage is between that of the protologism (freshly coined) and neologism (new word) is a prelogism.

Popular examples of neologisms can be found in science, fiction (notably science fiction), films and television, branding, literature, jargon, cant, linguistics, the visual arts, and popular culture.

Former examples include laser (1960) from Light Amplification by Stimulated Emission of Radiation; robot (1941) from Czech writer Karel Čapek's play R.U.R. (Rossum's Universal Robots); and agitprop (1930) (a portmanteau of "agitation" and "propaganda").