Source : Webster's Revised Unabridged Dictionary (1913)

Slabby \Slab"by\, a. [Compar. {Slabbier}; superl. {Slabbiest}.]
   [See {Slab}, a.]
   1. Thick; viscous.

            They present you with a cup, and you must drink of a
            slabby stuff.                         --Selden.

   2. Sloppy; slimy; miry. See {Sloppy}. --Gay.