There are also celestial (ἐπουράνια) bodies, and bodies terrestrial (ἐπίγεια): but the glory of the celestial (τῶν ἐπουρανίων) is one, and the glory of the terrestrial (τῶν ἐπιγείων) is another. (1 Corinthians 15:40)From this passage we know the Greek terms for celestial and terrestrial. But what about telestial. We would need to have the two terms along with a third one. As it happens, there is a passage in the New Testament that provides it:
10 That at the name of Jesus every knee should bow, of things in heaven (ἐπουρανίων), and things in earth (ἐπιγείων), and things under the earth (καταχθονίων);This passage in Philippians provides us with the Greek term for telestial. The term καταχθονίος means under the earth. and provides the third counterpoint to the terms celestial (of the heavens) and terrestrial (of the earth). It also provides us with the etymology of telestial. The two companion terms come from Latin caelum "heaven" and terra "earth". With a knowledge of the Greek term, it should have some meaning of something under the earth. The best option is Latin tellus "soil, ground."
11 And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father. (Philippians 2:10–11)
Lest this seem far-fetched, it should be remembered that the visions of the three degrees of glory ends with an allusion to the passage in Philippians:
109 But behold, and lo, we saw the glory and the inhabitants of the telestial world, that they were as innumerable as the stars in the firmament of heaven, or as the sand upon the seashore;
110 And heard the voice of the Lord saying: These all shall bow the knee, and every tongue shall confess to him who sits upon the throne forever and ever; (Doctrine and Covenants 76:109–111)