Wikipedia
Adjuvilo is a 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.
Colas created a nearly complete grammar, but did not create a new vocabulary. Adjuvilo uses mainly the vocabulary of Ido with modifications according to the grammatical changes of Ido. Colas in some cases reestablishes the Esperanto forms of words and even constructed some new words like sulo for "sun" (Ido/Esperanto: suno) and dago for "day" (Ido: dio, Esperanto: tago).