What is the meaning of "Yish'ago"?
Rashi: This is present tense (they roar).
Radak: They raised their voices, confounded [Yisrael] and plundered them.
Malbim: They did not bite them yet, they only roared.
Who are "Kefirim"?
Rashi: They are kings. Radak - they are compared to young lions. Yisrael ask why this happened; the Navi answers, "you abandoned Hashem" (verse 17).
Malbim: They are young, lions, i.e. a small, weak and lowly kingdom.
What are "Artzo" and "Arav"?
Malbim: They are (a) The Klal of the Medinah, and (b) The individual cities, respectively. The Churban struck every individual city (Yeshayah 1:7).
What is the meaning of "Nitzsu"?
Rashi: They were burned. Radak - this is like "va'Titzas b'Sivchei ha'Ya'ar" - "Areichem Serufos Esh" (Yeshayah 9:17, 1:7).
Radak, based on Targum Yonasan: They were destroyed and made desolate. The root is Yatzas. It is written with a Hei at the end, and pronounced as if there is a Vov. This is like "Yadeinu Lo Shafchu" (Devarim 21:7) and similar verses.
Radak citing his father: They sprouted. A desolate place sprouts vegetation.
