Con-Lang

Esperanto is the world's most widely spoken constructed international auxiliary language. It was created by L. L. Zamenhof , a Polish ophthalmologist, and first published in 1887 under the pseudonym Doktoro Esperanto — "one who hopes". The language was designed to be politically neutral, easy to learn, and capable of serving as a common second language for international communication.

Ido is a constructed international auxiliary language created as a deliberate reform of Esperanto. Its name means simply "offspring" in Esperanto — an acknowledgment that it grew directly from L. L. Zamenhof's 1887 language, retaining its logical backbone while addressing perceived weaknesses.

Interlingua is a naturalistic international auxiliary language developed between 1937 and 1951 by the International Auxiliary Language Association (IALA) , chiefly under the direction of the linguist Alexander Gode . Unlike invented languages built from scratch, Interlingua was extracted from natural languages: its vocabulary comes from the common international stock shared by English, French, Italian, Spanish, and Portuguese, and its grammar is the simplest system that governs that vocabulary without distorting it.

Interslavic ( Medžuslovjansky in its own Latin script, Меджусловјанскы in Cyrillic) is a naturalistic zonal auxiliary language designed to be comprehensible to speakers of any Slavic language without prior study. Unlike purely artistic constructed languages, Interslavic is grounded entirely in the common Slavic heritage: its vocabulary, grammar, and phonology are derived statistically and historically from the real Slavic languages rather than invented from scratch.

Klingon — known in the language itself as tlhIngan Hol ("the Klingon language") — is a constructed language created by American linguist Marc Okrand for the Klingon alien species of the Star Trek franchise. It is one of the most fully developed and widely studied constructed languages ever created for a fictional setting.

Novial is a constructed international auxiliary language created by the Danish linguist Otto Jespersen (1860–1943), one of the most eminent grammarians and phonologists of his era. He introduced Novial in his 1928 book An International Language , presenting it as a reform and improvement upon Ido — itself a reform of Esperanto. The name "Novial" is a blend of Nov (new) + I nternational + Al ternative (or Auxiliari Lingue ), though Jespersen himself sometimes glossed it simply as "new international auxiliary language".