Rahabm.n. Rahab is the emblematic name of Egypt and is also used for the sea. In medieval Jewish folklore, Rahab is a mythical sea-monster.
Biblical usage
Egypt
Rahab is a poetical name for Egypt. It might have Egyptian origins that were accommodated to the Hebrew language. However, there is nothing revealing in the Coptic language.
I mention Rahab and Babel to those knowing Me, Lo, Philistia, and Tyre, with Cush! This was born there.YLT
Thou art ruler over the pride of the sea, In the lifting up of its billows, Thou dost restrain them. Thou hast bruised Rahab, as one wounded. With the arm of Thy strength, Thou hast scattered Thine enemies.YLT
Awake, awake, put on strength, O arm of Jehovah, Awake, as days of old, generations of the ages, Art not Thou it that is hewing down Rahab, Piercing a dragon!YLT
Creation narratives in Biblical texts
Before the Medieval adoption of "Rahab" to mean demon or sea-beast, the name also appears in Psalm 89: 5-12 and Isaiah 51:9-10. Rahab, in these passages, takes the meaning of primeval, chaotic, multi-headed sea-dragon or Leviathan. It is often assumed that long before the Jewish mythos, the ancient Jews emulatedthe creation fables told by their predecessors. The Babylonians, for example, told of a sky-god, Marduk, and a sea-goddess, Tiamat, battling for supreme power over the other gods, in the Enûma Eliš. It can be speculated these two characters in the Babylonian myth are parallel to the creation stories found in the Biblical passages containing the name Rahab.
Rahab as insolence or pride
In Isaiah 30:7, rahaḇ becomes a proverbial expression that gives an allusion to the Hebrew etymology insolence.
Yea, Egyptians vanity, and in vain do help, Therefore, I have cried concerning this: `Their strength to sit still.YLT
God will not withdraw his anger, the proud helpers do stoop under him.KJV
He divideth the sea with his power, and by his understanding he smiteth through the proud . KJV
Jewish folklore
In medieval Jewish folklore, Rahab is a mythical sea monster, a dragon of the waters, the "demonic angel of the sea". Rahab is also seen as a deity in the text. Rahab represents the primordial abyss, the water-dragon of darkness and chaos, comparable to Leviathan and Tiamat. Rahab later became a particular demon, inhabitant of the sea, especially associated with the Red Sea..