The word 奠基石 is formed by combining three characters: 奠 (diàn), meaning to establish or lay down; 基 (jī), meaning foundation; and 石 (shí), meaning stone. Together, they create a compound noun where 奠 modifies 基 to indicate the establishing of a foundation, and 石 specifies the material, resulting in a term for a cornerstone or foundation stone used in construction ceremonies.