Rahab (H7292) means to storm against, to act boldly or arrogantly, to importune. The noun rahab (H7293) refers to the mythological sea dragon of chaos — a creature of pride and defiance against God. Together they carry the meaning of aggressive, stormy boldness.
In the OT's poetic books, Rahab appears as a cosmic enemy of God — a sea dragon representing the forces of chaos that God defeats at creation (Job 9:13; 26:12; Ps 89:10). When God 'cut Rahab to pieces' (Isa 51:9), it is an image of the Exodus — God splitting the sea, defeating chaos for His people. The name is repurposed in Psalm 87:4 to refer to Egypt. This word arc moves from chaos-monster to defeated Egypt to the theological truth: God conquers all that storms against Him.
Rahab as a sea monster belongs to ancient Near Eastern mythology that the OT both engages and subverts. Where other nations worshiped sea-chaos deities, Israel confessed that YHWH had already defeated such forces. The NT parallel is in Revelation where the dragon (Satan) is conquered by the Lamb (Rev 12-13). Note: Rahab the prostitute (H7343) is a different word — a hero of faith in Joshua 2.