A Ger can mean a stranger, foreigner and many other things but what is the origin? I have heard the Ibn Ezra say that it comes from the Hebrew word Gargir meaning a certain type of berry because it is severed form the branch. Can anyone provide a source.
What is the ger? A convert, an outsider, or a Jew?
Contrary to what many people think, the Torah does not consider the ger to be a convert. For example, while Numbers 15:15 gives the ger rights to bring gift offerings, the ger is more like a protected foreigner (נכר) living in the land of Israel. While the ger is not an Israelite, he lives “within your gates,” and is so vulnerable socially and economically, must be protected. They are compared to widows and orphans. But Deuteronomy does consider a ger to be in some part of the covenant, implying a mixed-status. But while Deuteronomy sees the ger as a poor serf, the Priestly ger share almost equal status. The “thetorah.com,” recognizes that scholars date the Priestly sources around the times of the Second Temple, approaching rabbinic Judaism. But ger in Deuteronomy is not a circumcised proselyte, a convert, or Jew. Actually, the circumcised ger does not become a civilian but is “as a citizen” (כְּאֶזְרַח).
Tannaitic literature Midrash, Pesahim 8:8 treats the Passover sacrifice (Exodus 12) as conversion. It seems to state that uncircumcised gers are permitted to practice the offering. However, the circumcision of a ger does not make him a Jew any more than an uncircumcised Jew is still a Jew. All it requires is that its participants be circumcised, whether Jew or not, makes no difference.
In the Septuagint, the Greek translation of the Hebrew Bible, the term prosēlytos (προσήλυτος) is used for ger. This Greek word means “stranger,” not a proselyte. Paroikos (πάροικος) in Greek means “living among,” “joining,” or “neighbor," denoting foreigners. These people, according to the Greek Septuagint do not adopt Israelite behavior or identity. Although the Greek proselytos (via Latin) is the source of the English word "proselyte," meaning convert, it meant at that time simply foreigner.
In fact, in the days of the Second Temple, there was no legislated transition ritual that turned a gentile into a Jew. Actually, it was more of a continuum, rather than a dichotomy. Even Josephus is silent on the ritual of conversion. However, later as time progressed, the rabbis understood גר תושב (ger toshav) to mean a non-Jew who fulfills some biblical commandments while (ger she-nitgayyer) or (ger tzedek), meaning “a righteous ger," refers more to a convert who underwent the practice of conversion.
 See Shaye Cohen's The Beginnings of Jewishness: pg, 140-162.
 See conversion of King Izates of Adiabene