فلك

Etymology 1
Belonging to the root.

Noun

 * 1) orbit, rounded course
 * 2) sphere
 * 3) sky, outer space, universe, (figurative) heaven
 * 4) orb
 * 5)  falak, ouroboros
 * 1)  falak, ouroboros
 * 1)  falak, ouroboros

Usage notes
This word is the ancient version of كون (which has been used in Arabic since the sixth century, unlike فلك which has been used since ever), it means roughly Heaven, but unlike English, the it isn’t limited to positive and divine worlds, as it can also describe the dwellings of demons and spirits. See also ذر (a spiritual universe in Islamic cosmogony, named as such because the offspring of Adam had come out his back as if they were small ants).

Etymology 2
Belonging to the root. Perhaps, however, unrelated to etymology 1 and instead from.

Noun

 * 1) ship