Cosmoglottics is a science that investigates world languages (or, universal languages); more specifically about universal artificial languages, its study and construction.
Sergey N. Kuznetsov makes an opposition between cosmoglottics, the science about universal planned language, and interlinguistics, the science about international languages and communication, founded by Otto Jespersen in 1931.
References
Cosmoglottics Wikipedia(Text) CC BY-SA