The Language Question

Fantasy and science fiction necessarily refer to imaginary languages but often do not divulge a single word of those languages:

uniquely, JRR Tolkien invented languages, then imagined their speakers, then wrote stories about the speakers;

in CS Lewis' Ransom Trilogy, Solar is spoken throughout the Solar System except on Thulcandra, the Silent Planet, Earth;

in Poul Anderson's History of Technic Civilization, the dominant languages of Terra, Ythri and Merseia are Anglic, Planha and Eriau, respectively;

Anderson's Time Patrollers speak Temporal among themselves;

his time traveling Wardens and Rangers use diaglossas;

ERB's Martians all speak the same Barsoomian, however isolated or hidden their communities;

his Tarzan learns the simian language (?);

SM Stirling's Martians speak dialects of Demotic (popular) Modern which has an "...Imperative-Condescentative tense..." (In The Courts Of The Crimson Kings, p. 65), although, in Terrestrial languages, the imperative is a mood, not a tense.

One dialect of Demotic is so ancient that it is "...almost the High Tongue..." (p. 39). Thus, we are told of the Martian language that it is ancient or modern, popular or high, but not (yet) what it is called.