Probably from 'avah (in the sense of crying out after); lamentation; also interjectionally Oh! -- alas, woe.
see HEBREW 'avah
H188. oy
אוֺי interjection (onomatopoetic; compare , ) woe! an impassioned expression of grief and despair: usually with dative לִי אוֺי Isaiah 6:5 woe to me! for I am undone, so 24:16; Jeremiah 10:19; 15:10; לָנוּ אוֺי woe to us! 1 Samuel 4:7-8, Jeremiah 4:13; 6:4; לִי אוֺינָֿא 4:31; 45:3; לָנוּ אוֺינָֿא Lamentations 5:16. With the 2nd or 3rd person often implying a denunciation; מוֺאָב אוֺילְֿךָ Numbers 21:29 (= Jeremiah 48:46) 13:27; Ezekiel 16:23 repeated לָח אוֺי אוֺי; Isaiah 3:9 לְנַפְשָׁם אוֺי 3:11; Hosea 7:13; 9:12 ("" לָהֶם שֹׁד). With a voc. (or implicit accusative) Ezekiel 24:6, 9 הַדָּמִים עִיר אוֺי; absolute Numbers 24:23. Used as a substantive Proverbs 23:29 אוֺי לְמִי ("" אֲבוֺי לְמִי).