And the LORD said unto Joshua, This day have I rolled away the reproach of Egypt from off you. Wherefore the name of the place is called Gilgal unto this day. The reproach of Egypt - Their being uncircumcised made them like the uncircumcised Egyptians; and the Hebrews ever considered all those who were uncircumcised as being in a state of the grossest impurity. Being now circumcised, the reproach of uncircumcision was rolled away. This is another proof that the Israelites did not receive circumcision from the Egyptians; for they could not have considered those in a state of abomination, from whom they received that rite by which they conceived themselves to be made pure. The Israelites had this rite from Abraham; and Abraham had it from the express order of God himself. See Genesis 17:10 (note), and the note there.
The place is called Gilgal - A rolling away or rolling off. See the note on Joshua 4:19, where the word is largely explained.