Probably from 'al; nay, i.e. (softened) if -- but if, yea though.
see HEBREW 'al
H432. illu
אִלּוּ conjunction (often in Mishnah; Aramaic אִילּוּ, , from אִין, , and לוּ) if, though, only in late Hebrew, Ecclesiastes 6:6; Esther 7:4.