Is rabble a word in the Scrabble Dictionary

Yes, rabble is playable

...and is worth 13 points.

Found in the following dictionaries

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

"Rabble" Definition

noun

A tumultuous crowd; a mob.
An iron bar used to stir and skim molten iron in puddling.
Any of various similar tools or mechanically operated devices used in roasting or refining furnaces.
The lowest or coarsest class of people. Often used with the.
The lowest class of people.

verb-transitive

To stir or skim (molten iron) with an iron bar.

verb

To insult or assault by or as a mob.