Greek Meaning: The name Alejandro is a Greek baby name. In Greek the meaning of the name Alejandro is: Defender; protector of mankind. Famous Bearer: Alexander the Great. American Meaning: The name Alejandro is an American baby name.In American the meaning of the name Alejandro is: Defender; protector of mankind.Famous Bearer: Alexander the Great. Spanish Meaning: The name Alejandro is a Spanish baby name.In Spanish the meaning of the name Alejandro is: Defends mankind.n American the meaning of the name Alejandro is: Defender; protector of mankind. Famous Bearer: Alexander the Great. Spanish Meaning: The name Alejandro is a Spanish baby name. In Spanish the meaning of the name Alejandro is: Defends mankind.