"Special" D'ni Words
There are some words in the D'ni language that do not have a direct and nice translation right now. This is a short listing of those particular words.
gemeDet Gemedet - "Six in a Row", a three dimensional game played by the D'ni. Also the name of one of the Ages that Aitrus owned. (Source: Book of Ti'ana)
re'DantE re'dahntee - The tweezers used to play Gemedet. Whether the apostrophe indicates that the word is really 'dahntee is unknown. If that is true (which I personally doubt), then that would mean that the apostrophe has some pronunciation. (Source: Book of Ti'ana)
cor bak chor bahkh - A D'ni food, a meat filled roll (Source: Book of Ti'ana)
IKa nijuex ikhah nijuets - Some kind of D'ni food. (Source: Book of Ti'ana)
yertis yertis - A plant existing in Riven. (Source: From Myst to Riven)
ytrahm - Gehn's word for a frog. (Source: Riven)
The actual origins of this word - it's Marty spelled backwards; Marty O'Donnell was one of the sound guys for Riven. I'll let you find out on your own why exactly they gave his name to the frogs.
DaS dahsh - The dome towers. (Source: From Myst to Riven)
hEK heek - Gehn's cane which serves double duty as a weapon. (Source: From Myst to Riven)
ugrat ugraht - The pillars in the Wahrk lake. (Source: From Myst to Riven)