Is slabber a word in the Scrabble Dictionary

Yes, slabber is playable

...and is worth 14 points.

Found in the following dictionaries

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

"Slabber" Definition

noun

A saw for cutting slabs from logs.
Source: Wiktionary
A slabbing machine.
Source: Wiktionary
Moisture falling from the mouth; slaver.
Source: Wiktionary

verb

To cover, as with a liquid spill; soil; befoul.
Source: Wiktionary
To eat hastily or in a slovenly manner, as liquid food.
Source: Wiktionary
To let saliva or other liquid fall from the mouth carelessly; drivel; slaver.
Source: Wiktionary
To wet and befoul by liquids falling carelessly from the mouth; slaver; slobber.
Source: Wiktionary