Definition of slab line:
(n) :
(nautical) A line or small rope by which sailors haul up the foot of the mainsail or foresail.
(n) :
(climbing) A climbing route that is characterized by a relatively low-angle rock face or slab that lacks significant vertical features such as large holds or overhangs.
(n) :
(optometry) The line on a pair of lenses that indicates where a slab-off prism has been applied.
(n) :
(electrical engineering) A central conductor surrounded by two planar ground slabs.
(n) :
(Texas, slang) An informal car club for customized slabs (luxury pre-1980 General Motors vehicles)