Is cotton a word in the Scrabble Dictionary

Yes, cotton 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)

"Cotton" Definition

noun

Any of various shrubby plants of the genus Gossypium, having showy flowers and grown for the soft white downy fibers surrounding oil-rich seeds.
Any of various soft downy substances produced by other plants, as on the seeds of a cottonwood.
The crop of these plants.
The fiber of any of these plants, used in making textiles and other products.
Thread or cloth manufactured from the fiber of these plants.

verb-intransitive

Informal To come to understand. Often used with to or onto: "The German bosses . . . never cottoned to such changes” ( N.R. Kleinfield).

biographical name

John 1585–1652 Am. (Eng.-born) Puritan clergyman.
Charles 1630–1687 Eng. author & translator.

verb

To come to understand .
To take a liking .