Smith's Bible Dictionary 
Meon'enim. (Enchanters). The Plain Of Meonenim . An oak or terebinth, or other great tree. Judges 9:37. The meaning of Meonenim, if interpreted as a Hebrew word, is Enchanters or "Observers Of Times", as it is elsewhere rendered Deuteronomy 18:10; Deuteronomy 18:14. In Micah 5:12, it is Soothsayers .
Easton's Bible Dictionary 
Judges 9:37 Deuteronomy 18:10,14 2 Kings 21:6 Micah 5:12 Genesis 35:4
Morrish Bible Dictionary 
Not the 'plain' but the 'oak' of Meonenim, that is, the Enchanter's Oak, or 'the regarders of times' as in the margin. Judges 9:37 .
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
(Hebrews Meonenim') occurs in the Auth. Vers. ( Judges 9:37) in the proper name Elon-Meonenim ( אֵלוֹן מְעוֹנַים ), "the plain;" or, as it should be rendered, The Oak Of Meonenim (Sept. ῞Ηλων Μαωνενίμ ''V. R Δρύος Ἀποβλεπόντων , marg. "regarders of times"). Meonenim (variously rendered in the Auth. Vers. "sooth-sayers," "regarders of times," etc.) means Sorcerers , and is derived either from עוֹנָה , "time" ( Exodus 21:10), from עִיַן , "the eye," or else, which is more probable, from עָנָן , "a cloud;" it means. therefore, those dealers in forbidden arts who-observe times, or practice fascination, or take auguries from the signs of the sky. (See Divination).
Whatever was its original meaning, Meonenim was afterwards used in a perfectly general sense ( Deuteronomy 18:10; Deuteronomy 18:14; 2 Kings 21:6; Micah 5:12) for wizards. In this article, therefore, we are only concerned with "the oak of the sorcerers," a celebrated tree near Shechem, mentioned in Judges 9:37, where Gaal, son of Ebed, the Shechemite conspirator, standing "in the entering of the gate," saw the soldiers of Abimelech first on the hilltops, and then in two companies, of which one approached by the "oak of the sorcerers," which is evidently pointed out as a conspicuous land-mark. It would be the better suited for this purpose because oaks are rare in Palestine, except in the hills. For other trees used as land-marks, see Genesis 35:8; 1 Samuel 22:6; x,3; 14:2, etc. Now it happens that in Scripture no less than Four other celebrated trees in the immediate neighborhood of Shechem are prominently mentioned in connection with important events, and it is interesting to inquire whether all or any of these can be identified with " the sorcerer's oak." (See Oak).
1. In Genesis 12:6 we are told that Abraham ".passed through the land unto the place of Sichem, unto the oak of Moreh" (Sept . Τὴν Δρῦν Τὴν Ὑψηλήν ), where the use of the singular points to One tree of note, although at Shechem there was a grove of oaks ( Deuteronomy 11:30). It was, therefore, in all probability conspicuous for size and beauty, and the vision which Abraham there commemorated by building an altar would add to it a sacred and venerable association. (See Abraham).
2. In Genesis 35:4 we read that Jacob, on his way to Bethel, took from his family all the strange gods which were in their hand, and all their ear- rings which were in their ears, and hid them under the oak which was by Shechem ( הָאֵלָה אֲשֶׁר עַםאּשְׁכֶם ). The use of the article in this verse is not, indeed, absolutely decisive, but would lead naturally to the supposition that this tree was the one. already so famous in the religious history of the Israelitish family. That אֵלָה is used (Sept. Τερεβινθος ) and not אֵלוֹן , is a consideration of no importance, for it seems certain that the two words are synonymous (see Gesenius, Thesaur . p. 50, 51), or at any rate are used interchangeably. (See Terebnth).
3. In Joshua 24:26, Joshua, after addressing the assembled tribes at Shechem. "took a great stone and set it up there under an oak ( The oak, הָאִלָּה ) that was by the sanctuary of the Lord." The use of the definite article again renders it probable that this is the same tree as that which had been connected with the' memories of Abraham's vision, and Jacob's rejection of idolatrous possessions; and the probability is strengthened into certainty by the fact that Joshua's injunction in ver.14 ("put away the gods which your fathers served on the other side of the flood") is almost identical with that which Jacob had addressed to his family on that very spot ( Genesis 35:2) some 300 years before. Kalisch, indeed, objects that a " sanctuary of the Lord" would never have been erected at the place of idols (Genesis , p. 586); but, to say nothing of the fact that Several of the Jewish high-places seem to have been also connected with the, worship of the Canaanites, a place where idols had been buried, and so rejected, and scorned, would surely be most fitted for the sanctuary', especially if it had been hallowed by a previous protest made by the great forefather of the race against the idolatry which there surrounded him ( Genesis 12:7).
4. In Judges 9:6, we read that " all the men of Shechem... made Abimelech king, by the oak (AV. plain) of the pillar that was in Shechem" ( מֻצָּב אֲשֶׁר בַּשְׁכֶם עַםאּאֵלוֹן . The word מֻצָּב , Mutstsab , is very obscure. and Jerome's version, "quercus quas stabat in Sichem," seems to show that it may once have Followed אֲשֶׁר . The Sept. renders it Πρὸς Τῇ Βαλάνῳ ( Τῇ Ευρετῇ Τῆς Στάσεως Τῆς Ἐν Σικίμοις , where Στασις . means "a military station," a rendering approved, by Gesenius (Thesaur. p. 904), who compares Isaiah 29:3. Our AV. refers it to the sacred stone set up by Joshua, and this seems a very probable rendering, from the constant use of the word Matstsebah for similar erections ( Genesis 28:18; Exodus 24:4; 2 Kings 3:2; Micah 5:13, etc.). It seems further possible that during the confusions which prevailed in the country after Joshua's death, the stone which he had erected beneath it, and which he invested, even though only in metaphor, with qualities so like those which the Canaanites attributed to the stones they worshipped -during these confused times this famous block may have become sacred among the Canaanites, one of their "matstsebahs" [(See Idol)], and thus the tree have acquired the name of "the oak of Mutstsab" from the fetish below it. - The argument that this tree cannot be identical with Jacob's, because That is spoken of as Near ( עַם ), and This as In ( ב ) Shechem, is quite unconvincing, both because the use of the prepositions by Hebrew writers is by no means minutely accurate, in this way corresponding to. their general Ἀγεωγραφία , and because Shechem may. mean the District Round The City , as well as the city itself. -(For a decisive case in point, see Joshua 5:13, where the Vulgate rightly renders בַּירַיחוֹ by " In Agris Urbis Jericho.") We believe, therefore, that all these trees are one and the same, which thus becomes connected with four most memorable events in the lives of Abraham, Jacob, Joshua, and Abimelech.
Was this tree also the " oak of the sorcerers ?" There might at first seem to be a positive reason against the identification, because (1.) The name " sorcerers," or " enchanters," would not be particularly suitable to the tree, which Kalisch also thinks might with more propriety have been called the " oak of idols," or of "witchcraft," than the oak of enchanters (Genesis, p. 586); and (2.) Because Gaal evidently points to the Elon-Meonenim at a distance from the city, whereas Jacob's tree was in it. Of this second argument we have already disposed; and-besides, Gaal's expression may merely mean that one company was on the road which led by "the sorcerer's oak." As regards the first argument, the Elon Meonenim may have been the same as Jacob's tree, and yet not have received its name from the idols and amulets which Jacob buried there. The close connection of ear-rings with talismans and magic arts is well known, and in the Chaldee the word used for ear-ring is קִדַּישָׁא so that it does seem reasonable to suppose that there is a connection between the name and the event. But if not, May Not The Nane Have Originated In Some Use Made Of The Tree By The Priests And Necromancers Of The Neighboring Shrine Of Baal-Berith ? ( Judges 8:33; Judges 9:36). If it be asked how it was that a tree so sacred as this could have received An Opprobrious Name , it must be borne in mind that this name only occurs on the lips of Gaal, who in all probability was an aboriginal Canaanite of the old royal family ( Judges 9:28; comp. Genesis 34:2; Genesis 34:6), and who would therefore be likely to call the tree by a name derived from its associations with idolatrous rather than with Jewish worship. (See Gaal).