The Hebrew verb gaar means to rebuke, to reprove, or to rebuke authoritatively — often with a sense of God or a leader exerting dominance over a threatening force. It is used both in interpersonal rebukes and dramatically of YHWH rebuking the sea, enemies, or evil.
Gaar carries the idea of authoritative restraint — the rebuke of a superior that brings an inferior force to submission. When God rebukes the sea (Psalm 104:7; Nahum 1:4), the waters flee. When he rebukes adversaries, they are undone. This word underlies Jesus' rebuke of the storm and of demonic spirits in the Gospels.
Theologically, gaar reveals that God's word has power — a rebuke from YHWH accomplishes what it commands. It also calls leaders and believers to exercise righteous correction.