What is the meaning of "Atzmu Li"?
Rashi: They increased in front of Me.
Radak: This refers to [great] quantity and quality. It says "Li", for I am pained over it. This was in the days of Achaz. Pekach ben Remalyahu killed 120,000 of Yehudah in one day (Divrei ha'Yamim II, 28:6), and the women remained widows.
What is the meaning of "Al Em"?
Rashi: This is Yerushalayim, which was a great city in Yisrael.
Radak: "Em" is a congregation or family, like Um and Umah.
Malbim: Each widow [brought a youth to lie with her. He was Mezanah with her and ravaged her.
What is "Bachur"?
Radak, Targum Yonasan: It is a Klal; it refers to many youths. The same applies to "Shesh Me'os Rechev Bachur" (Shemos 14:7).
Why does it say "ba'Tzaharayim"?
Rashi: All their hidden matters are revealed in front of Me (like afternoon, when it is light).
Radak: I brought plunderers against congregation of youths in the afternoon. It was not at night, the way thieves come. The youths' strength did not help them.
Malbim: [The youth was Mezanah with the widow and ravaged her] openly.
What is the meaning of "Hipalti Aleihem Pis'om Ir u'Vehalos"?
Rashi #1: I suddenly brought troops of the city (Mahari Kara - of Melech Bavel) and great terror.
Rashi #2: "Ir" refers to hatred, like "va'Yhi Arecha" (Shmuel I, 28:16), "u'Fishrei l'Arach" (Daniel 4:16).
Radak: Against the Em, I made destruction of cities. "Behalos" is like suddenly.
Malbim: I brought revelation of Ervah against the widows suddenly.