Source : Webster's Revised Unabridged Dictionary (1913)

Lok \Lok\, Loki \Lo"ki\, n. [Icel. Loki, perh. akin to lokka,
   locka to allure, entice.] (Scandinavian Myth.)
   The evil deity, the author of all calamities and mischief,
   answering to the African of the Persians.

Source : WordNet®

Loki
     n : (Norse mythology) trickster; god of discord and mischief;
         contrived death of Balder and was overcome by Thor