Eimek Achor

In today's perek of the Nach Yomi for Avraham program, Yehoshua ch. 7, the place where Achan is judged and executed for taking from the spoils of Yericho is called Eimek Achor, and he himself is referred to as Ocheir Yisroel (in the genealogies of Divrei HaYamim). The term Eimek Achor is also used by Hoshei'a (ch. 2), who says that it will turn into Petach Tikva, an entrance of hope, and Yeshaya (ch. 65), who says that it will turn into an area of cattle pasturing. The description ocheir is also used by Yiftach, to refer to his daughter, Ach'av and Eliyahu to refer to each other, and Yonasan, to refer to his father, due to his decree during a certain battle against the P'lishtim that the people were required to fast until the P'lishtim were utterly beaten.

I had always thought that "ocheir" meant one who makes stumble, but today's research indicated that it means to make cloudy, turbid, or stirred up - like "mayim achurim" used in the mishnah (?) in reference to what may or may not be used for netilas yadayim.

What does this mean? I don't know.