A foundational term for consecration and moral purity, originally meaning "devoted to the gods" in classical Greek. In biblical usage, it overwhelmingly carries positive connotations: temples and sacred spaces are ἅγιος; persons who are holy or pure before God bear this designation; "the Saints" (οἱ ἅγιοι) refers to God's people; and the Holy Spirit is πνεῦμα ἅγιον. The Septuagint adopted this term to translate Hebrew קָדוֹשׁ, reinforcing the concept of separation unto God. Classical Greek occasionally used it negatively ("accursed"), but this sense is rare and absent from biblical texts. The term may share roots with Sanskrit *yajati* ("sacrifice"), pointing to ancient Indo-European concepts of ritual dedication.