means A flat slab — of stone, clay, wax, paper, or now a thin touchscreen computer — used for writing, marking, or displaying information.

from From Old French 'tablete,' a little 'table,' which traces back to Latin 'tabula,' a board or plank. The same 'tabula' gives us 'table' itself — so a tablet is literally a small flat surface, a meaning that's carried it from clay tablets pressed in Mesopotamia to stone tablets in scripture to the glowing glass slab in your hand. The pharmaceutical 'tablet,' a little flat-pressed pill, follows the same shape logic.