Abarim Publications' online Biblical Hebrew Dictionary
There are two roots of the form רבע (rb') although they don't seem to be related. One of them is connected to a verb of the form רבץ (rbs).
The root רבע (rb') lies at the heart of a group of words that all have to do with the cardinal number four. The Hebrews experienced numbers differently than we do. This is primarily demonstrated by the absence of ciphers in Hebrew. Numbers were spelled out as words (which makes calculus difficult; in modern Oriental languages numbers are represented much more effectively in language and that's why Oriental kids, on average, are far better at calculus than Western kids, explains Malcolm Gladwell in chapter eight of his book Outliers), but these words often meant something else as well. Calculus is virtually absent from the Bible, and quantities reported of obviously don't convey the mathematical rigor that we moderns are used to. To the Hebrews actual amounts seem to have been of recessive importance to what amounts may have meant in their narrative contexts, and items that came in a certain amount were associated with other items that show up in that same quantity (e.g. 10 commandments, 10 plagues, 10 camels of Abraham; that's no coincidence).
There is some similarity between the words רבע (raba'), meaning four and the adjective רב (rab), meaning a great many, or the verb רבה (raba) meaning to be (a great) many. It seems to reflect the natural (animal) number sequence of "none, one, two, three, many, a great many, a continuum (so many you don't see the separate units)". In that sense, the word four means "a small quantity more than 3" and it reflects greatness or vastness (think of the four winds of heaven or the four corners of the earth; neither heaven nor earth have anything to do with the cardinal number 4).
On the other hand, the need to actually recognize and give a name to the quantity 4 demonstrates an increase in complexity of transactions and considerations. In our modern world, beyond-3 numerical agility and number conservation marks the intelligence of children of about six years old, but somewhere between the emergence of intelligence (or rather: the cultural expression of intelligence) and where we are now, human culture at large had to cross that threshold. And that means that the root רבע (raba') also marks an incredible intellectual achievement: the reckoning of 4, which is arguably a greater achievement that the invention of the number zero. Or as Stanislas Dehaene writes in his wonderful book The Number Sense:
"Animals do not possess a digital or discrete representation of numbers. Only the first few numbers — 1, 2 and 3 — can be discriminated with high accuracy. As soon as one advances towards larger quantities, fuzziness increases" (page 27), and "Our remote ancestors probably named only the numbers 1, 2 and 3. Then a series of inventions successively emerged . . . " (page 247).
Also note that Hebrew authors sometimes used metathesis to drive a point. The root רבע (rb') is the reversal of the root עבר ('abar) meaning to cross over, and from which derive the names Abarim, Eber and Hebrew. Perhaps their assumption of this root as their epithet of identity, the Hebrew thinkers illustrated their belief that wisdom merely based on factual knowledge was void, doomed to fail and had to be superseded by what they called the fear of YHWH (Proverbs 3:5, see also Ephesians 3:19). Another people's name that is formed from these three letters is עבר ('arab), or Arab.
The Biblical "four"-words are:
- The masculine and feminine noun ארבע ('arba'), representing the cardinal number four, or rather a small quantity more than 3 (Genesis 2:10). The regular plural of this word, ארבעים ('arba'im) is usually explained to mean forty, but there's no real way of verifying this. In the Biblical narrative the word ארבעים ('arba'im) is most often used to describe a symbolic time span, such as the forty days it rained on Noah's Ark (Genesis 7:4), or the forty days Moses was on the mountain with the Lord, twice (Deuteronomy 9:9, 9:18). Israel wandered in the wilderness for forty years (Deuteronomy 2:7); Joshua was forty when Moses sent him out to spy (Joshua 14:7), and he stayed away forty days (Numbers 13:25). Moses died when he had lived three times forty years (Deuteronomy 34:7). And four of the seventeen judges held office for "precisely" forty years — namely Othniel (Judges 3:11), Deborah (Judges 5:31), Gideon (Judges 8:28) and Eli (1 Samuel 4:18). And right before the rise of judge Samson, Israel was subdued by the Philistines for "precisely" forty years (Judges 13:1). The chronology of the Book of Judges adds to 400 years, which is much longer than the time between the end of the Exodus and the beginning of the monarchy (about two centuries).
- The denominative verb רבע (raba'), meaning to square in the sense of giving something or having four sides. This verb only occurs in the form of a participle: squared (Exodus 27:1, 1 Kings 7:5, Ezekiel 45:2).
- The masculine noun רבע (reba'), meaning a fourth part (Exodus 29:40, 1 Samuel 9:8). This noun in plural is used in the meaning of having four sides (Ezekiel 43:16).
- The masculine noun רבע (roba'), also meaning a forth part (Numbers 23:10, 2 Kings 6:25).
- The masculine adjective רביעי (rebi'i) and the feminine adjective רביעית (rebi'it), representing the ordinal number fourth (Genesis 1:19, Exodus 28:20, Numbers 7:30).
- The adjective רבע (ribbea'), meaning "pertaining to the fourth" (Exodus 20:5, Numbers 14:18).
The root verb רבע (raba') is probably an Aramaic variant of the verb רבץ (rabas; see next). It means to lie down or lie stretched out. This curious verb is used predominantly in a sexual sense (lying down with animals: Leviticus 18:23, 19:19, 20:16). In Psalm 139:3 this verb is supposedly used in the regular sense of laying down, but it's juxtaposed with the noun ארח ('orah), which means path, but which can often be translated with lifestyle or company kept.
In Hebrew, sexual intimacy is referred to by means of the verb ידע (yada'), meaning to know. If the root רבע (rb' I) refers to the kind of numerical agility that was ostensibly defeated by the invading Hebrews (told through the story of Arba and Hebron), our verb רבע (raba' II) must have seemed perfect to express sexual interaction between a woman and an animal, or the questionable antics of a Hebrew king.
The verb רבץ (rabas) means to stretch out or lie down, but usually in the sense of to repose or rest from exertion rather than to sleep of having intercourse. It's used of people (Isaiah 14:30, Job 11:19) and animals (Genesis 29:2, Ezekiel 34:14). Its derivations are:
- The masculine noun רבץ (rebes), meaning resting place or spot (Isaiah 65:10, Jeremiah 50:6).
- The masculine noun מרבץ (marbes), also meaning place or spot of rest (Ezekiel 25:5, Zephaniah 2:15).