adj. ancient
adv. in an ancient manner
n. ancientness
v. to age greatly, make or become ancient; to pass out of time or memory

Alduin, feyn do jun, kruziik vokun staadnau, voth aan bahlok wah diivon fin lein!
Alduin, Bane of Kings, ancient shadow unbound, with a hunger to swallow the world!
(Book, Songs of Skyrim)

Alduin, thuri! Boaan tiid vokriiha suleyksejun kruziik?
Alduin, my king (overlord)! Has the time arrived (flown) to restore (unkill) your ancient dominion (power-of-king)?
(Sahloknir, 00035F88)

Qethsegol vahrukiv daanik Fahliil kiir do Gravuun Frod, wo bovul ko Maar nol kinzon zahkrii do kruziik hokoron.
This stone commemorates the doomed elf children of the Autumn Field, who fled in Terror from the sharp swords of the ancient enemy.
(Word Wall for Maar, Dismay)

Refers to something old beyond memory, or powerful due to its age.

May share adjective suffix -iik with boziik ‘bold’ and bruniik ‘savage’.