Sweven (noun) is a Middle English word derived from the Old English word swefn which means sleep, dream or vision. It is further derived from the Proto-West Germanic word swefn and from the Proto-Germanic word swefną or swefnaz which both mean sleep. These are derived from the Proto-Indo-European word swépnos or supnós which means dream and from the Proto-Indo-European word swep which means to sleep. It is cognated with the Dutch word suf, meaning drowsy and the Middle High German word swēb, meaning sleep. Also with the Danish word søvn, the Icelandic word svefn, the Norwegian word søvn and the Swedish word sömn, all meaning sleep. Also with the Latin word somnus which means sleep, slumber or drowsiness.

Quotations:

1885, Sir Richard Burton, "The Thousand Nights and One Night":

"The queen went in to the Sultan and assured him that their daughter had suffered during all her wedding-night from swevens and nightmare".

"The Golden Legend", 1259–1266

"And then she said: Sir, hast thou seen the sweven that I have seen?"

More Info: en.m.wiktionary.org