the Flood: the world-covering water God brought over the earth in Noah's day
Hebrew has a full set of words for water that falls and water that rises: ordinary rain (מָטָר), a drenching shower (גֶּשֶׁם), a sudden cloudburst (זֶרֶם), the deep water below the earth (תְּהוֹם). This word belongs to none of them. It is held back for one event, the catastrophe of Noah's day, and twelve of its thirteen appearances sit inside Genesis 6 to 11. The story keeps the vocabulary sorted: the rain that falls for forty days is called rain, the springs that burst open belong to the deep, and this word names the whole disaster they add up to.
Because it names one particular event, it nearly always appears as "the" Flood, the way people say "the Depression" and expect no explanation. Genesis 6:17 even sets it beside the everyday word for water, so the sentence reads something like "the Flood, that is, water over the earth", as though the writer knew the rarer word needed a gloss for some readers. A verse later the narrative puts it the other way round and speaks of "the waters of the Flood".
One word ends up covering a small range because the story keeps returning to the same event from different angles: the water as it comes and rises, the water God promises will never come again, and finally the event as a bare date that Noah's remaining years and his sons' descendants are counted from. The scale is what holds those angles together. Genesis 7:11 has the water above the sky and the deep below let loose at once, so many readers hear in this word the coming apart of the world's first ordering rather than a very large storm.
One more thing marks the word off: it never travels into figures of speech. When prophets want judgment sweeping in like water they reach for a different word (שֶׁטֶף). This one stayed bonded to Noah, and the ancient Greek translators kept it that way, choosing a single Greek word for it (κατακλυσμός) that the New Testament then uses only of the same event.
Nuances
What the psalm means when it says the LORD sat "to the flood" in Psalm 29:10. The psalm is a storm hymn about God's kingship, and this is the only occurrence of the word outside the flood narrative of Genesis 6 to 11, so its referent here has been debated since the 1920s. The Hebrew preposition can be construed spatially ("enthroned over the flood") or temporally ("enthroned since before the flood"), and the noun itself has been taken as the Noahic deluge, as the celestial reservoir above the firmament, or as a personified chaos-water. The syntax alone cannot decide the question, and the parallel phrase "forever" in the second half of the verse has been claimed in support of more than one reading.
- contestedA retrospective reference to Noah's deluge: God, who sat in judgment over that water, reigns as king forever. This is the traditional reading and stands behind most English versions, and its strength is lexical consistency with the other twelve occurrences.; Derek Kidner, Psalms 1-72 (Tyndale Old Testament Commentaries; London: IVP, 1973), 127; Allen P. Ross, A Commentary on the Psalms (Grand Rapids: Kregel), on Psalm 29:10; Gerhard F. Hasel, "Some Issues Regarding the Nature and Universality of the Genesis Flood Narrative," Origins 5 (1978): 83-98, at 92-93
- minorityThe celestial ocean: the word denotes the reservoir of waters above the firmament, over which God is enthroned, rather than the historical deluge.; J. Begrich, "Mabbul: Eine exegetisch-lexikalische Studie," Zeitschrift fur Semitistik 6 (1928): 135-153; W. F. Albright, "The Babylonian Matter in the Predeuteronomic Primeval History," JBL 58 (1939): 91-103, at 98; Gerhard von Rad, Genesis: A Commentary, rev. ed. (Philadelphia: Westminster, 1972), 128; HALOT 2:541 (entertains the sense)
- contestedA Canaanite storm-god pattern lies beneath the psalm: the deity is enthroned over a conquered cosmic water, Cross rendering the noun "the Flood-dragon" and comparing Ugaritic mdb in KTU 1.101:1-2.; Frank Moore Cross, Canaanite Myth and Hebrew Epic (Cambridge, MA: Harvard University Press, 1973), 147 n. 4, 151-156; Mitchell Dahood, Psalms I: 1-50 (Anchor Bible 16; Garden City: Doubleday, 1966), 180; Peter C. Craigie, Psalms 1-50 (Word Biblical Commentary 19; Waco: Word, 1983), 246-249; John Day, God's Conflict with the Dragon and the Sea (Cambridge: Cambridge University Press, 1985), 57-60
- minorityThe preposition is temporal, on the model of Akkadian lam abubi "before the Deluge": the LORD has been enthroned since before the Flood, which he wielded as his instrument and never fought as an adversary.; David Toshio Tsumura, "'The Deluge' (mabbul) in Psalm 29:10," Ugarit-Forschungen 20 (1988): 351-355; David Toshio Tsumura, Creation and Destruction: A Reappraisal of the Chaoskampf Theory in the Old Testament (Winona Lake: Eisenbrauns, 2005)