Kedushah is a Hebrew word meaning "holiness". The term is frequently used in Judaism to describe God, and worldly items can also have holy status.
Kedushah is also the name of several prayers recited during Jewish prayer services. They have in common the recitation of two Biblical verses - Isaiah 6:3 and Ezekiel 3:12. These verses come from prophetic visions in which angels sing the verses as praises to God.
This prayer can be found on page 236 for the Shabbat prayers in the Chabad Tehillat Hashem Annotated Edition.
