The Aramaic adjective yatstsib means certain, sure, fixed, or true. It appears in the Aramaic sections of Daniel, where it is used as a formal affirmation — "the thing is certain" — often by those reporting to Nebuchadnezzar or Darius. It corresponds to the Hebrew concept of emet (truth) as something established and unalterable.
The repeated use of yatstsib in Daniel ("The thing is certain...") underscores the absolute reliability of divine revelation and prophetic word. When Daniel and his friends report truths to kings, those truths are yatstsib — fixed, not negotiable. The word appears at pivotal moments of divine disclosure, reminding readers that what God reveals is unshakeably certain — empires rise and fall, but God's word stands fixed.