Proto-Esperanto is the modern term for any of the stages in the evolution of L. L. Zamenhof's language project, prior to the publication of Unua Libro in 1887.

Arcaicam Esperantom or Arqhaicam Esperantom, is a constructed auxiliary sociolect for translating literature into Esperanto created to act as a fictional 'Old Esperanto', in the vein of languages such