The phrase "slab design" refers to the process of planning and constructing a flat, horizontal surface, like a floor or a ceiling, typically made of concrete. Full definition
Despite the choice of premium materials, the phone still has a somewhat bland look, failing to really differentiate itself from other standard rectangular slab designs on the market. (techspot.com)
The device basically features a rectangular slab design, with a full metal unibody construction that puts its build quality at par with a lot of current generation flagships. (androidauthority.com)
The two devices also offer the OmniBalance flat - slab design which is associated with all Xperia smartphones, from the lower - end to the flagship models. (pocket-lint.com)