Dovahkiin is the word
dragon-born in dragon tongue, it is used in the elder scrolls games, as a myth or legend until in "The elder scrolls IV - oblivion" where you help the dovahkiin, in "the elder scrolls V - skyrim" you ARE the dovahkiin.
The only NPC(s) that use the word dovahkiin instead of "
dragon-born" are:
The greybeards, paartharax, mirmulnir (this is the first
dragon you fight, they say "noooooooo, dovahkiin!" When defeated, so that is why it counts) and Alduin, the main terror in skyrim's main quest.
Dovahkiins are naturally skilled in using shouts (or in the dragon tongue, thu'ums) such as:
Unrelenting
force, fire breath, become ethereal and my personal favorite, slow
time. Shouts are made up of 3 words of power that are in the dragon tongue.
Dovahkiin, dovahkiin naal ok
zin los vahriin,
way Dein vokul mafaeraak ahst Vaal!
-an extract of the skyrim theme