Is peanut a word in the Scrabble Dictionary

Yes, peanut is playable

...and is worth 11 points.

Found in the following dictionaries

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

"Peanut" Definition

noun

A peanut-shaped piece of polystyrene, used in cushioning items during shipment.
A prostrate southern Brazilian plant (Arachis hypogaea) widely cultivated in tropical and warm temperate regions, having yellow flowers on stalks that bend over so that the seed pods ripen underground.
Informal A very small amount of money; a trifling sum.
Slang A person small in stature.
Slang A person who is regarded as being insignificant.

adjective

Slang Having little or no importance; insignificant: peanut politicians.