לוּ

1. if (stating a case which has not been, or is not likely to be, realized):
  a. followed by perfect (so mostly), Deut 32:29 לו חכמו ישׂכילו זאת if they had been wise (which they are not), they would understand this; Mic 2:11 (apodosis וְהָיָה); Judg 8:19; Judg 13:23 להמיתנו לא לקח לו ׳חפץ י if J. had desired to slay us, he would not have taken, &c.; 1Sam 14:30; 2Sam 19:7.
  b. followed by imperfect Ezek 14:15 if I were to send, &c. (but read probably אוֺ, compare vEzek 14:17 vEzek 14:19).
  c. followed by participle, 2Sam 18:12 וְלֻא אָנֹכִי שֹׁקֵל and though I should be weighing 1000 pieces of silver upon my hand, I would not, &c.; Ps 81:14-17 לו עמי שֹׁמֵעַ לי if my people were hearkening to me, . . . quickly would I bow down, &c.
  d. followed by יֵשׁ Job 16:4. — With the apodosis omitted, Gen 50:15 לוּ יִשְׂטְמֵנוּ if Joseph were to hate us (how should we fare then ?).

2. If only ...! i.e. O that! would that! (compare εἰ γάρ, εἴθε) usually followed by perf., as Num 14:2 (twice in verse) לוּ מַתְנוּ if only we had died in the land of Egypt! Num 20:3; Josh 7:7 וְלוּ הוֺאַלְנוּ וַנֵּשֶׁב Isa 48:18; Isa 63:19 followed by יֵשׁ Num 22:29 followed by imperfect Gen 17:18 לו יחיה O that Ishmael might live before thee! Job 6:2 followed by jussive Gen 30:34 כדברך לו יהי; followed by imperative Gen 23:13 אם אתה לוּ שׁמעני if thou — O that thou wouldst hear me! (+ probably vGen 23:5 לאמר ׃ לוּ שׁמעני for ׳לאמרֹ לוֺ ׃ שׁ, and similarly vGen 23:15). — Read also probably לֻא for Masoretic לֹא Judg 21:22 (with כִּי עַתָּה), 1Sam 13:13; 1Sam 20:14 (twice in verse); Job 9:33 (followed by יֵשׁ); and perhaps Job 14:4 (Ew Kö).