אלל

Abarim Publications' online Biblical Hebrew Dictionary

אלל אול יאל

Across two root groups — אלל ('ll) and אול ('wl) — the Hebrew language seems to insist on a direct relationship between oaks and foolishness/worthlessness, although the connection might simply lay in the act of protruding: a tree protrudes up in the air, a foolish person protrudes from convention, and a worthless item protrudes from the economy of useful things. Then there are two roots יאל (y'l), of which one is comparable to one of the two roots אול ('wl), while the other denotes the showing of willingness or determination:

אלל I

The root אלל ('ll I) isn't used as verb in the Bible, and its meaning is assumed to be to be weak or insufficient. Its sole derivative is the masculine noun אליל ('elil), meaning worthlessness or a worthless thing. In the Bible this noun is used predominantly for vain worship or idols (Leviticus 19:4, Isaiah 2:8, Ezekiel 30:13). Zechariah speaks of a worthless shepherd (Zechariah 11:17) and Job laments worthless physicians (Job 13:4). In Jeremiah 14:14 occurs the variant אלול ('elul).

אלל II

The root אלל ('ll II) is also not used as a verb, and we're entirely in the dark about its meaning. Its Biblical derivatives are:

The masculine noun אלון ('allon), meaning oak (Isaiah 44:14, Zechariah 11:2, Amos 2:9). Quite a few locations were known for their oaks. The prophet Isaiah specifically mentions the oaks of Bashan (Isaiah 2:13), and Deborah, the maid of Rachel, was buried by Allon-bacuth (the Oak of Weeping) near Bethel (Genesis 35:8).
The feminine version of the previous noun, אלה ('alla), also meaning oak, is used only once, in the troublesome verse Joshua 24:26, which speaks of an oak (a girl-oak) in the sanctuary of the Lord. No such tree actually exists anywhere in the Bible, and we're all baffled at the meaning of this reference.

The etymology of both roots אלל ('ll) is uncertain, and while scholars assume that there are indeed two, and that these two have nothing to do with each other, they may very well be one!

It may seem curious to see these two (or three) closely related words carry such different meanings, but the word אלון ('allon) — meaning oak and mostly symbolizing strength — also occurs in the prophets as synonym for a place of pagan worship (Hosea 4:13) or the material from which idols were made (Isaiah 44:14).

One special instance of our word אלון ('allon) occurs in Joshua 19:33. Some translations read here about "Allon of Zaanannim," while others have "the oak in Zaanannim". BDB Theological Dictionary refutes all together that this particular instance of אלון ('allon) comes from our root group אלל ('ll) and refers to yet another root group: אול ('wl I and II), which, curiously enough, reflects another and similar disparity in meaning:

אול I

The assumed root אול ('wl I) yields the following derivations, all having to do with foolishness:

The adjective אויל ('ewil), meaning foolish (Job 5:2, Hosea 9:7).
The adjective אולי ('ewili), also meaning foolish (Zechariah 11:15 only).
The feminine noun אולת ('iwwelet), meaning foolishness or folly (only in the Book of Proverbs: 12:23, 14:18, etc.).

אול II

The assumed root אול ('wl II) yields the following derivations, all having to do with protruding or sticking out:

The masculine noun אול ('ul), which, depending on the context, may mean belly (Psalm 73:4) or leading man (2 Kings 24:15).
The masculine noun אולם ('ulam), meaning porch (of the temple — 1 Kings 7:19, Ezekiel 8:16). This word is identical to a strong adversative (see below)
The masculine noun איל ('ayil) generally denoting that what sticks out: a ram (in the sense of leader of a herd? - Genesis 31:38, Exodus 29:32, Leviticus 9:14), projecting pillar or door post (1 Kings 6:31, Ezekiel 40:9), leader or chief (2 Kings 24:15, Exodus 15:15) or terebinth (that's a kind of oak; a prominent, lofty tree, says BDB Theological Dictionary - Genesis 12:6, Isaiah 1:29).
The feminine noun אלה ('elah), also meaning terebinth (Genesis 35:5, Joshua 24:26). Note that this word is spelled identical to the demonstrative pronoun אלה ('elleh), meaning these, or אלה ('eloah) meaning god or God (follow the link for more info on these words).
The feminine noun אלון ('elon) also meaning terebinth (Genesis 12:6, Deuteronomy 11:30). Note that this feminine noun is nearly identical to the masculine noun אלון ('allon) derived from root אלל ('ll II)
The masculine noun אילם ('elam) also meaning porch. This word occurs about half a dozen times, all in Ezekiel 40-41 (Ezekiel 40:37, 41:15).
The masculine noun איל ('ayyal) means stag or deer (Deuteronomy 12:15, Isaiah 35:6). In its most famous occurrence of Psalm 42:2, this masculine noun is used as a feminine word. And note that the Hebrew that describes a "deer which pants for water" also describes a "fool who pants for instructions."
This last masculine noun properly made feminine yields the feminine noun אילה ('ayyala), meaning doe (Genesis 49:21, Jeremiah 14:5).

יאל I

The verb יאל (ya'al I) is comparable or related to אול ('wl I; says BDB Theological Dictionary). It means to be foolish and is used in two distinct ways:

In the sense of to show wicked folly (Numbers 12:11, Jeremiah 5:4).
To become fools (Isaiah 19:13, Jeremiah 50:36).

יאל II

The verb יאל (ya'al II) is comparable or related to אול ('wl II; says BDB Theological Dictionary, but how is not very clear). It denotes a show of willingness to go along with something (Exodus 2:21, Joshua 7:7), and in that sense also translatable with to be pleased or determined (Joshua 17:12, Judges 1:35), or even to undertake some action with which one agrees (Genesis 18:27, Deuteronomy 1:5).

אולם

The adverb אולם ('ulam) is spelled and pronounced identically to the masculine noun אולם ('ulam), meaning porch, which was derived from the root אול ('wl II). Our adverb is a "strong adversative" (as BDB Theological Dictionary calls it), translatable with words like: but, but indeed, however, nevertheless. It's used when the flow of a thought needs to come to an abrupt halt and be forced another way (Genesis 48:19, Job 1:11, 1 Kings 20:23).

אולי

The adverb אולי ('ulay) looks like it comes from either root אול ('wl), but BDB Theological Dictionary suggests it's probably a contraction of או ('o; meaning or) and לו (lu; meaning if), or a variant of the adverb לולא (lule'; meaning if not). This adverb is "often associated with personal or national crisis" (says HAW Theological Wordbook of the Old Testament) and is translated with perhaps or suppose (Genesis 16:2, Numbers 22:6, Job 1:5).