ETYM Old Eng. slabbe, of uncertain origin; perhaps originally meaning, a smooth piece, and akin to slape, Icel. sleipr slippery, and Eng. slip, v. i.
Thick piece of something.

(dialect chiefly England) Thick, viscous

1. To remove an outer slab from (as a log); to divide or form into slabs
2. To cover or support (as a roadbed or roof) with slabs
3. To put on thickly