Is sheep a word in the Scrabble Dictionary

Yes, sheep 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)

"Sheep" Definition

noun

A person regarded as timid, weak, or submissive.
Any of various usually horned ruminant mammals of the genus Ovis in the family Bovidae, especially the domesticated species O. aries, raised in many breeds for wool, edible flesh, or skin.
Leather made from the skin of one of these animals.
One who is easily swayed or led.
Any of various hollow-horned typically gregarious ruminant mammals (genus ) related to the goats but stockier and lacking a beard in the male.