From the same as 'ab (apparently through the idea of prattling a father's name); properly, a mumble, i.e. A water skin (from its hollow sound); hence a necromancer (ventriloquist, as from a jar) -- bottle, familiar spirit.
see HEBREW 'ab
H178. ob
אוֺב noun masculineJob 32:19 skin-bottle, necromancer, etc. — absolute ׳א Leviticus 20:27 8t.; plural אֹבוֺת 19:31 7t. —
1 skin-bottle, only plural חֲדָשִׁים אֹבוֺת new (wine-) skins Job 32:19.
2 necromancer, in phrase יִדְּעֹנִי אוֺ אוֺב necromancer or wizard Leviticus 20:27 (H; usually translated 'a man also or woman that hath a familiar spirit or that is a wizard' RV; but better a man or a woman, if there should be among them, a necromancer or wizard; no sufficient reason for exceptional use of phrase here); ׳א וְיִדְּעֹנִי Deuteronomy 18:11; 2 Chronicles 33:6 = 2 Kings 21:6 (where ׳א וידענים); וְהַיִּדְּעֹנִים הָאֹבוֺת Leviticus 19:31; 20:6 (H) 1 Samuel 28:3, 9; 2 Kings 23:24; Isaiah 8:19 (where repres. as chirping & muttering, in practice of their art of seeking dead for instruction, probably ventriloquism, & so ᵐ5) 19:3.
3 ghost, Isaiah 29:4 תְּצַפְצֵף אִמְרָתֵח וּמֵעָפָר קוֺלֵח מֵאֶרֶץ כְּאוֺב וְהָיָה and thy voice shall be as a ghost from the ground and from the dust thy speech shall chirp (so Ge MV Ew De Che and others, but chirping might be of necromancer, as 8:19).
4 necromancy בַּעֲלַתאֿוֺב אֵשֶׁת a woman who was mistress of necromancy 1 Samuel 28:7 (twice in verse); (> RSJPh xiv, 127 f makes אוֺב primarily a subterranean spirit, and significant. 2 only an abbreviation of ׳בעלתא etc.); בּאוֺב קסם divine by necromancy 28:8, which seems to be interpretation of 1 Chronicles 10:13 בא ׳שׁאל inquire by necromancy. (In these three examples אוֺב is usually interpreted as ghost or familiar spirit conceived as dwelling in necromancer; but this apparently not the ancient conception.)