Webster’s Revised Unabridged Dictionary · 1913 Slabby Slab′by (·by̆), 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. ‹ Slabbing Slack ›