Something sacred is holy, devoted to a religious ceremony, or simply worthy of awe and respect. Jerusalem is a sacred place for many religions, just as Fenway is a sacred place for Red Sox fans.
Sacred is an adjective used to describe a person or thing worthy of worship or declared holy. It usually appears in a religious context, but an object or place set aside for a particular purpose can also be sacred. Sacred spaces and items are intended to be treated with care and respect — even if it's just your shrine to Brad Pitt.