Abarim Publications' online Biblical Hebrew Dictionary
The root ארב ('arab) describes a breaching of and subsequent emergence from a safe perimeter. As verb it's mostly deployed in military or predatory contexts, in which aggressors or predators lay in safe hiding, until they emerge to attack their enemy or prey. As such this verb is mostly translated with to lie in wait or to ambush (Joshua 8:4, Judges 9:32, Lamentations 3:10). Its derivatives are:
- The masculine noun ארב ('ereb), meaning a lying in wait (Job 37:8 and 38:40 only).
- The masculine noun ארב ('oreb), meaning ambush or trickery (Jeremiah 9:7 and Hosea 7:6 only).
- The feminine equivalent of the previous: ארבה ('orba), also meaning trickery (Isaiah 25:11 only).
- The feminine noun ארבה ('aruba), meaning window or sluice. This word is used for the opening through which smoke may escape a kitchen (Hosea 13:3), or doves their cot (Isaiah 60:8) or the gaze of watchers their house (Ecclesiastes 12:3; this reference is probably not about an old person's physical eyes but rather his or her ability to look ahead into the future). Note that since our root describes a passing through a perimeter from the inside out, the "windows of heaven" are not those media through which destructive rain or constructive blessings come to us, but those media through which YHWH sends these things to us (Genesis 7:11, 2 Kings 7:2, Malachi 3:10). Note that this word and the previous one are spelled identically to the word ארבה (arbeh), denoting a kind of locust, from the root רבה (raba I), meaning to be or become great or numerous.
- The masculine noun מארב (ma'arab), literally meaning place of ambush (Joshua 8:9, Judges 9:35) or a person who lies in an ambush (Psalm 10:8, 2 Chronicles 13:13).