Constructed languages introduced in the 1910s

Quenya () is a constructed language, one of those devised by J. R. R. Tolkien for the Elves in his Middle-earth fiction.

Adjuvilo is a constructed language created in 1910 by Claudius Colas under the pseudonym of "Profesoro V. Esperema". Although it was a full language, it may not have been created to be spoken. Many believe that as an Esperantist, Colas created Adjuvilo to help create dissent in the then-growing Ido movement. Colas himself called his language simplified Ido and proposed several reforms to Ido.

'''''' () are the linguistic experiments in sound symbolism and language creation of Russian Cubo-Futurist poets such as Velimir Khlebnikov and Aleksei Kruchenykh. Zaum is a non-referential phonetic entity with its own ontology. The language consists of neologisms that mean nothing. Zaum is a language organized through phonetic analogy and rhythm. Zaum literature cannot contain any onomatopoeia or psychopathological states.