Set apart and not to be treated casually. Sacredness is a decision a community keeps, not a property a thing has.
Latin sacer (holy, set apart, dedicated), source of sacrare (to consecrate); sacredness was never a property found inside a thing, but a status a community conferred and kept agreeing to.
Set apart from casual handling, by a decision a group keeps making together rather than by any property a thing carries on its own.