Why will there be thorns in the castles?
Rashi: Thorns and bushes normally sprout in ruins. Kimush and Cho'ach are kinds of thorns.
Malbim: At a time of Shalom, they dwell in the castle. At a time of war, they dwell in the fortification. Now, both of them will be [desolate, and] full of thorns.
What is "Sanim"?
Rashi: It is an evil beast.
Metzudas David: It is a snake 1 .
Rashi (Kesuvos 49b) and other Rishonim equate Tanim and Tanin. Radak (Divrei ha'Yamim I, 6:1) says that [sometimes] Mem and Nun are the same in names. Shemos 7:10, 15 equates it to a snake; Mizrachi (7:9, citing Radak) says that a land Tanin is a snake, but a sea Tanin is a fish.
What is "Chatzir"?
Radak: This is like Chatzer with a Tzeirei. Targum Yonasan says, a place [for ostriches].
Malbim: It is grass. It will be for ostriches, which eat even broken glass, and also thorns.
