The word “holy” is “qodesh” in Hebrew (Strong’s H6944) which comes from the root “qadash” (H6942) which means “to be clean (ceremonially or morally)”. The Ancient Hebrew Lexicon 2700 explains it as: “Set apart from the rest for a special function”. Bible Project explains the Set-Apartness of Elohim in this video along with the following written explanation: “When referring to the holiness of God, the holiness definition takes on a much richer meaning. … The holiness of God is a term used in the Bible to describe both His goodness and His power.