Generally used to describe the indescribable; something beyond our limited human comprehension.
Philosopher: After years of contemplating in my parents' basement, I have come to the conclusion God is arlen.
Emo girl: After the breakup, I felt so...so.... arlen! I even slit the word onto my left wrist.
Dude: I suppose you're expecting a sex-related example to complement the definition. But I'm in an arlen mood so I won't give one!