Tzafnas Paneiach

"Pharaoh called Yosef's name Tzafnas-Paneiach" (Bereshis 41:45) צָפְנַת פַעְנֵחַ

1. Rashi explains: "Revealer of hidden things." The sale of Yosef was hidden from all, save those who participated and the purchasers. There was one exception, our Patriarch Yitzchak (see Rashi on 37:35 d.h. "va'yeivk"). To all it was hidden, except it was clarified to Yitzchak (יצחק), whose name has the same numerical value as "paneiach." N'vei Shalom points out that that Rashi is switching the order of the words with his explanation. A literal translation would be "the hidden he clarifies."
2. The Medrash Rabbah 90:4 brings in the name of Rabbi Yochonan that the word "Paneiach" is a composite of "pa," as in the word form "hofia," meaning "appears," and "nach," as in the word form "noach," eases. This means that when his explanation of a hidden matter appears, it is readily acceptable and eases the minds of those who were previously puzzled.
3. Rabbeinu Menachem Azariah says that this composite word's first component comes from the word form "efeh" (Yeshiyahu 42:14), - I will raise my voice. "Nach" is the same as before. Thus, Paneiach means he raises his voice and announces (his explanation). However, this is only according to the translation of the Ibn Ezra in Yeshiyahu. Targum translates "efeh" as "uncovers."
4. The Rada"k says that this is an Egyptian name.
5. Rabbi Sheis Harofeh (a Rishon) says that these are Egyptian words and we do not know their meaning and this is why Targum only repeats these words. However, our Targum does translate these words like Rashi.
6. Rabbi Shlomo Ashtruk says that these words mean "governor," one who supplies the needs of the masses.
7. The Ralba"g says that this was the name of Paroh's god (a very small g).
8. It was a good thing that this idea to give another name to Yosef entered Paroh's mind because otherwise if his name was left as Yosef, his brothers would have caught on to his identity. (Akeidas Yitzchak and Chasam Sofer)
9. The Baalei Tosfos say that this is an acronym for "Tzadik Pitpeit Neged Taavoso Ino Nafsho Chinom." (a Tzadik fought a desirous soul; Potifar afflicted his soul, for no reason).
10. R' Machir z"l Hy"d (Spain; 14th century) writes: The Hebrew letters of this name are the initials of "Tzaddik panah negged ta'avato; Potiphar inah nafsho chinam" / "The righteous one (Yosef) turned aside in the face of his desire (for Potiphar's wife); Potiphar oppressed him for no reason." (Avkas Rocheil ch.56)
11. The Baal HaTurim says that this is forms the first letters of 'Tzofeh, Fodeh, Navi, Somech, Poser, Anav, Navon, Chozeh' (One with foresight, redeemer, prophet, supporter, interpreter, humble, wise and seer). He also says that "Tzafnas Paneiach" has the numerical value of "megaleh nistaros" revealer of hidden things.
12. The base inclinations that are hidden deep inside a person were open and evident to Yosef. (Rabbi Volf Strikiver in Zeir Zohov)
13. There is a well-known commentary of a Rishon on the Torah called Paneiach Roza. It was authored by Rabbeinu Yitzchak b"R' Yehudoh haLevi. Earlier editions of this work were called Paneiach Rozi, but more recently printed in a most beautiful manner with the addition of the commentary of Rabbi Meir Horowitz z"l, called "Roza d'Meir, by Rabbi Yoseif Dov Asia shlit"a. He writes that Roza rather than Rozi is correct and that this name was specifically chosen by the author because each of these words (פענח רזא) has the numerical value of 208, equal to that of Yitzchak, the name of its author.

The Rogatchover Gaon, Rabbi Yosef Rosen (1858-1936), also known by the name of his main work Tzafnas Paneach, was one of the prominent Talmudic scholars of the early 20th century, known as a “Gaon” (genius) because of his photographic memory and razor sharp mind. His main work, a commentary on Maimonides, was published during his lifetime, as well as five volumes of responsa. The remainder of his surviving writings appeared in the United States many years after his death; all are titled Tzafnas Paneach "decipherer of secrets.”

The Rogatchover is remembered for his breadth of Torah knowledge and caustic wit. He did not suffer inadequacy lightly. He was similarly reputed to rarely quote any rabbinic authority after the Rambam, and avoided recent rabbinic works of the Achronim in favor of the Rishonim (those preceding the late 15th century). His responses to queries of Jewish law could be enigmatic and cryptic.