Is hyena a word in the Scrabble Dictionary

Yes, hyena is playable

...and is worth 10 points.

Found in the following dictionaries

Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)

"Hyena" Definition

noun

Any of several carnivorous mammals of the family Hyaenidae of Africa and Asia, which feed as scavengers and have powerful jaws, relatively short hind limbs, and coarse hair.
Any of several large strong nocturnal carnivorous Old World mammals (family Hyaenidae) that usually feed as scavengers.