What is the meaning of "Galosi"?
Rashi: I removed.
What is "Cherpas Mitzrayim"?
Rashi citing R. Moshe ha'Darshan: Pharaoh said (Shemos 10:10) "there is Ra'ah in front of you", i.e. a star called Ra'ah. It is a sign of blood. Moshe said to Hashem (Shemos 32:12) "why should the Egyptians say b'Ra'ah Hotzi'am to kill them"? They did not know that it is blood of Milah. The Erev Rav among Yisrael used to taunt them about this, until Yehoshua circumcised them.
Radak: The fathers left Egypt, and the sons were Arelim, like the Egyptians. Orlah is Cherpah (shame), like it says "Ki Cherpah Hi Lanu" (Bereishis 34:14).
Malbim: They were slack about Milah, because they had not yet purified from the idolatry of Egypt; there, they were Arelim. You 'inherited' this shame from Egypt.
Why did they call the place Gilgal?
Radak: From "Galosi" it is proper to say Galal; the first letter of the verb was repeated. 1 We find that names based on verbs have an extra or missing letter, e.g. Noach from (Bereishis 5:29) "Yenachamenu" (the root is Nachem; the Mem was omitted) and Shmuel from (Shmuel 1 1:20) "She'altiv" (a Mem was added).
The root of Galosi is Galal. (PF)