X was a Persian satrap of Caria. In 353 B.C. when X died, his queen Artemisia, who was also his sister, built him the most splendid tomb in the known world. X thus, finds its name as one of the seven wonders of the world.
The word X also features in English meaning ‘external free-standing building constructed as a monument enclosing the interment space or burial chamber of a deceased person or persons’.