What is the meaning of "Shvi Domem"?
Radak: Sit silently; your voice should not be heard, like "v'Hayah k'Ov me'Eretz Kolech" (29:4). Domem is a noun. Or, it is a generic adjective for masculine and feminine, like Reikam 1 . Also "Uri l'Even Domem" (Chabakuk 2:19, is an adjective for a feminine noun).
We explain like Kli Paz' text of Radak. 'Reikam' is used often for masculine, e.g. "Reikam Shilachtani" (Bereishis 31:42), and also for feminine "v'Cherev Sha'ul Lo Sashuv Reikam" (Shmuel II, 1:22), "Al Tavo'i Reikam" (Rus 3:17). 'Reik' is not used for feminine, rather, "Reikah" (Yechezkel 24:11).
Why does it say "u'Vo'i va'Choshech"?
Radak: You should not be seen, for the verdict on you is to be ashamed. People should not hear or see you, for you used to be the mistress of kingdoms, and now you are captive and exiled.
Malbim: No man should see you outside, for you have no hope to ever return to your grandeur.
What will not persist?
Radak: They will no longer call you "mistress of kingdoms." Malbim - they will not call you so at any time.
