Something sacred is set apart as holy and not to be treated lightly. A sacred place, sacred texts, sacred to the memory of.
It belongs first to religion — sacred music, a sacred site — where it means dedicated to a god and protected by that dedication. The wider sense is anything a person or group holds beyond question: nothing is sacred, a sacred principle. Note sacred cow, meaning an idea or institution nobody dares criticise, which comes from the status of cattle in Hinduism, and that holy and sacred overlap without being interchangeable.
1adjectivesacredSet apart as holy.
“The whole hill is sacred and nothing may be built on it.”
2adjectivetreatedTreated as beyond question.
“Saturday morning was sacred and nobody scheduled anything.”
Too few real examples of this word to estimate which sense is commonest.
sacred is a quality of being set apart.
Latin sacer meant holy and, oddly, also accursed — both senses of set apart from ordinary use. Sacrifice, sacrament and consecrate are the same root, and the word's original meaning is separation rather than goodness.
Middle English
sacred
English, today
sacred
Built from
From Middle English sacred, isacred, past participle of sacren, sakeren (“to make holy, hallow”), equivalent to sacre + -ed.
Etymology from Wiktionary, CC BY-SA