arulo an artificial language intended for international use as an auxiliary language
basic english a simplified form of English proposed for use as an auxiliary language for international communication; devised by C. K. Ogden and I. A. Richards
esperantido an artificial language based on Esperanto and Ido
esperanto an artificial language based as far as possible on words common to all the European languages
europan an artificial language proposed as an auxiliary European language
idiom neutral an artificial language proposed for use as an auxiliary international language; based on Volapuk but with a vocabulary selected on the basis of the maximum internationality of the roots
interlingua an artificial language proposed for use as an auxiliary international language; based on words common to English and the Romance languages
ido an artificial language that is a revision and simplification of Esperanto
volapuk one of the first artificial language constructed for use as an auxiliary international language; based largely on English but with some German and French and Latin roots