Neum means utterance, declaration, or oracle. It appears about 376 times, almost exclusively in the phrase 'declares the LORD' (neum YHWH). It functions as a prophetic formula authenticating divine speech.
Neum YHWH ('declares the LORD') is the prophet's stamp of divine authority. It asserts that the words spoken are not human opinion but divine revelation. This formula appears throughout the prophetic books, grounding every promise and warning in God's own authority.