means A thin, flat slab — usually of fired clay, stone, or ceramic — laid in rows to cover a floor, wall, or roof.

from From Old English 'tigele', a borrowing of Latin 'tegula', meaning a roof-tile — itself from the verb 'tegere', 'to cover' (the same root that shelters us in 'protect' and 'detect'). So a tile is, at heart, simply 'a covering thing', a name it has worn faithfully since Roman roofs.