Abarim Publications' online Biblical Hebrew Dictionary
The forms עוץ ('us) and עצה ('asa) are structurally closely adjacent, although it's not clear whether they are actually etymologically related. Still, to any Hebrew poet or Hebrew audience, the relationship between the two was probably quite obvious:
The verb עוץ ('us) means to counsel or regard. It occurs only twice in the Bible, and is therefore much more specific than simply a thinking-over. It denotes deep contemplation on reality and justice:
Isaiah 8:10 reads, "Counsel a counsel and it is broken . . . (Green)," or "devise a plan and it will be thwarted . . . (NAS)".
In the scene that relates the repulsive incident that almost wiped out the tribe of Benjamin, a Levite takes the body of his gang-raped and killed concubine, and cuts it into 12 pieces and sends them throughout the territory of Israel. He adds the message, "Set yourselves on this, take counsel and speak" (Judges 19:30).
The verb עצה ('asa I) means to shut. It occurs in several cognate languages with similar meaning. In the Bible it occurs only once, in Proverbs 16:30: "he that shuts his eyes".
The meaning of the root-verb עצה ('asa II) is unclear and it doesn't appear to be used in the Bible. Its derivatives are:
- The common Semitic masculine noun עץ ('es), primarily meaning tree. Our noun is used to denote a single standing tree (Genesis 2:9), or a group of trees (Genesis 2:16). It is used to denote wood for kindling (Joshua 9:23), wood as a building material (Genesis 6:14, 2 Kings 12:13), and items made of wood (Exodus 7:19, Deuteronomy 19:5). And hence it may be used to denote (wooden) idols (Deuteronomy 4:28) or gallows, stake or similar means of execution (Genesis 40:19, Deuteronomy 21:22). The theological meaning of the Biblical tree (from the two trees in Paradise related to the fall of man, to the cross of Christ, to the restored Tree of Life as witnessed by John the Revelator - Revelation 22:2) seem to promote a relationship with the verb עוץ ('us) meaning to counsel or regard.
- The feminine noun עצה ('esa), meaning trees collectively. This noun occurs only once, in Jeremiah 6:6.
The meaning of the root-verb עצה ('asa III) is also unclear. It has only one derivative, the masculine noun עצה ('aseh), denoting either the spine or else a certain bone close to the tail of an animal. It's used only once, in Leviticus 3:9, and the relationship with the previous group of words that denote trees is rather obvious to anyone with some poetic sense (like the author of Job, for instance, who writes of the Behemoth that he bends his tail like a cedar; Job 40:17).