רעע

Abarim Publications' online Biblical Hebrew Dictionary

רעע רעה

There are two roots רעע (ra'a') and three roots רעה (ra'a) and one root רוע (rw'). Internally, the meanings of these clusters are convincingly aligned, and the most fundamental meaning of this cluster obviously has to do with compartmentalization or separation. This could be a good thing when the emphasis lies on the getting together of two separated parts — hence the word רע (rea'), meaning friend — but it's a bad thing when a fruitful unity is compromised — hence the word רע (ra'), meaning evil:

רעע I

The root רעע (ra'a' I) isn't used in the Bible and there's no telling what it might have meant. But its derivatives are ubiquitous in the Bible:

The masculine noun רע (ra'), meaning evil (BDB Theological Dictionary counts two separate masculine nouns; HAW Theological Wordbook of the Old Testament lists one). The concept of evil is difficult and much more complicated than a simple opposite of טוב (tob), meaning good. It's not a product of the devil (Isaiah 45:7), nor is it the result of the fall (Genesis 2:17). And that means that whatever רע (ra') is, it was made by God to be part of a perfect world. As a fallen concept, however, it now contains badness of quality (Genesis 41:19), sadness (Ecclesiastes 7:3), distress or calamity (Jeremiah 42:6) and injury (Psalm 73:8). It may describe harmful acts as well as harmful words (Genesis 24:50) and even rotten fruits (Jeremiah 24:2) or ugly cows (Genesis 41:19).
The verb רעע (ra'a') is the verb associated with the previous noun. It means to be or do bad or evil: to be displeasing (Numbers 11:10), to be sad (Deuteronomy 15:10), to be injurious (Psalm 106:31), to be wicked (Genesis 38:10).
The adjective רע (roa'), is the adjective associated with the noun (Genesis 47:9, Exodus 21:8).
The feminine noun רעה (ra'a) is the feminine version of the previous noun (Isaiah 47:11, Judges 15:3).

רעע II

The verb רעע (ra'a' II) is probably a loan word from Aramaic. It's equivalent to the Hebrew verb רצץ (rasas), which means crush or break in pieces. But note that in Isaiah 45:7, the word רע (ra'), meaning evil, is used juxtaposed with שלום (shalom), meaning whole or unbrokenness, suggesting that "evil" in essence is brokenness, or the existence of space between elements that designed to be firmly connected.

Our verb רעע (ra'a') is used about eight times, in the meaning of literal breaking something (Jeremiah 11:16), or figuratively in the sense of brokenness by God due to sin (Job 34:24).

רעה I

The verb רעה (ra'a I) means to pasture, graze or tend. This verb stems from deep antiquity, where it was used as honorary title for rulers. The verb occurs all over the Old Testament and may usually be translated with either pasture or feed. It's also used in expressions such as "feeding on folly" (Proverbs 15:14), or "feeding on ashes" (Isaiah 44:20).

Where in English the word shepherd brings to mind someone who leads sheep somewhere or guards them, in Hebrew it's about someone who feeds them (by taking them somewhere and keeping them safe). There's no noun that means shepherd. The word רעה (ra'a) is an active participle meaning he/she who shepherds. This verb's derivatives are:

The masculine noun רעי (re'i), meaning pasture (1 Kings 5:3)
The masculine noun מרעה (mir'eh), meaning pasture or pasturage (Genesis 47:4, Isaiah 34:14).
The feminine noun מרעית (mar'it), meaning pasturing (Jeremiah 23:1), pasturage (Hosea 13:6).

רעה II

The verb רעה (ra'a II) means to associate with or be a friend of. As a verb it occurs seven times; once in the Psalms (Psalm 37:2) and six times in Proverbs (Proverbs 13:20). Its derivatives are:

The masculine noun רע (rea'), meaning friend or companion. It expresses an association ranging from intimate friend (Genesis 38:12) to companion (Exodus 2:13) to some other guy (Genesis 11:3). This word occurs 187 times in the Old Testament. It is also this word that is commonly translated as "neighbor" in the well-known command from Leviticus: "You shall love your neighbor as yourself". (Leviticus 19:18, Matthew 19:19). Note that this exact same word is also produced by the next root.
The masculine noun רעה (re'eh), meaning friend (1 Kings 4:5).
The verb רעה (ra'a), probably derived from the previous noun. It occurs once, in Judges 14:20. BDB Theological Dictionary lists this verb but HAW Theological Wordbook of the Old Testament doesn't.
The feminine noun רעה (re'a), meaning (female) companion (Judges 11:37 and Psalm 45:14 only).
The feminine noun רעיה (ra'ya), meaning attendant (only in the Song of Solomon).
The feminine noun רעות (re'ut), meaning female companion or mate (Isaiah 34:15, Esther 1:19). Note that this exact same word is also produced by the next root.
The masculine noun מרע (merea'), meaning friend or companion (Genesis 26:26, Judges 15:2).

רעה III

The root רעה (ra'a III) does not occur in the Bible, but in Aramaic — רעא (ra'a') — it means to take pleasure in or desire, and yields nouns that mean thought, opinion and disposition. Some scholars propose that this root and its derivatives are in fact a specialized group of words coming from root רעה (ra'a I). Also note that two of three derivations of this root are also produced by the previous root:

The masculine noun רע (rea'), meaning aim or purpose (Psalm 139:1).
The feminine noun רעות (re'ut), meaning longing or striving (Ecclesiastes 1:14).
The masculine noun רעיון (ra'yon), meaning longing (Ecclesiastes 1:17).

רוע

The verb רוע (rua') describes the production of a sudden burst of sound brought about by humans, namely an aggressive war cry (Joshua 6:10, 1 Samuel 17:52, Isaiah 42:13), a defensive alarm cry (Judges 7:21), a cry out of distress (Isaiah 15:4, Micah 4:9), a signal to start marching (Numbers 10:7), a triumphant shout (Jeremiah 50:15), a shout in applause (1 Samuel 10:24), or religious zeal (1 Samuel 4:5), or joy (Psalm 65:13). This verb is a bit of a chameleon; it appears formed as הריעו (Judges 15:14), הרעו (1 Samuel 17:20), יריע (Isaiah 42:13), תרועה (Joshua 6:5) and תרועת (Ezra 3:13).

The derivatives of this verb are:

The noun רע (rea'), meaning a shouting (Exodus 32:17, Job 36:33, Micah 4:9 only, but each of these occurrences is dubious and may rather be due to any of the above).
The feminine noun תרועה (teru'a), meaning alarm or war cry (Joshua 6:5, Amos 1:14), marching signal (Numbers 10:5, 2 Chronicles 13:12), shout for joy (1 Samuel 4:5, Ezra 3:13, Job 8:21).