A sacred trust. A sacred cow. A sacred agreement. The word "sacred" has been used to describe everything from the last hundred dollars in a savings account to a prized pair of sewing scissors that no one else is supposed to touch. The Japanese crown is considered to be sacred. In Christianity, Jesus' physical heart is so revered that it is the "sacred heart".
But what is the original meaning of the word "sacred"? From there, we can begin to find out how the meaning has evolved.
The origins of the word are as early as the Hittite language, where the term means "rite". In the Latin, the term can mean either sacred, or to make sacred. In Middle English, the word means to consecrate. All of these terms imply religious ritual and dedication to honor a deity.
The first dictionary definition of the term "sacred" states that the item or creature is dedicated and set apart for service or worship of a deity. The second definition indicates that the sacred item is worthy of religious veneration or entitled or worthy of respect. The third definition is exclusionary: the item is not secular or profane. The item is religious in a way that is respectful of the faith or deity. The last definition is that the item is inviolate or unassailable.
A strange, archaic definition has the item defined as "accursed", or as being under a curse.
A power, a being, or a realm of existence is considered to be sacred when people believe it to be at the core of existence, with power to transform life, and with the power to determine destiny
A sacred kingship has the ruler identified as the manifestation, agent, or mediator of a divine or supernatural realm or entity. In some kingdoms, the ruler is regarded as a God. Cleopatra of Egypt believed that she was the direct descendant of a God, as did many Roman and other rulers. The Pope of the Catholic Church is revered as the mediator between Catholic Humanity and God.
Sacred places are determined by the appearance of a holy figure, by its special features as a natural setting or place of official, historical or spiritual significance. Groves of trees, special stones, bodies of water or places built and then consecrated by ritual are common sacred places.
Just about everything from shirts to cows to texts have been declared or consecrated as sacred throughout the history of mankind, by virtually every culture, and under the auspices of a host of religions.
The best way to define "sacred" is then to be clear as to whether the use of the word is secular or vulgar (as with the best sewing scissors) or religious in its use.