The meaning of Tzofnas Paneach

Summary: Can we know the meaning or, due to our sins, did we lose this Hebraic knowledge? If the latter, can this serve as an excuse to confidently advance the traditional explanation, "Revealer of Hidden Things?"

Post: In parashat Miketz, Pharaoh renames Yosef. The pasuk, with Rashi:

45. And Pharaoh named Joseph Zaphenath Pa'neach, and he gave him Asenath the daughter of Poti phera, the governor of On, for a wife, and Joseph went forth over the land of Egypt.		מה. וַיִּקְרָא פַרְעֹה שֵׁם יוֹסֵף צָפְנַת פַּעְנֵחַ וַיִּתֶּן לוֹ אֶת אָסְנַת בַּת פּוֹטִי פֶרַע כֹּהֵן אֹן לְאִשָּׁה וַיֵּצֵא יוֹסֵף עַל אֶרֶץ מִצְרָיִם:
Zaphenath-Pa’neach: He who explains hidden things, and Pa’neach has no parallel in Scripture. — [from Targum Onkelos]		צפנת פענח: מפרש הצפונות, ואין לפענח דמיון במקרא:

This apparently based on Onkelos, which renders:

מא,מה וַיִּקְרָא פַרְעֹה שֵׁם-יוֹסֵף, צָפְנַת פַּעְנֵחַ, וַיִּתֶּן-לוֹ אֶת-אָסְנַת בַּת-פּוֹטִי פֶרַע כֹּהֵן אֹן, לְאִשָּׁה; וַיֵּצֵא יוֹסֵף, עַל-אֶרֶץ מִצְרָיִם.

וּקְרָא פַּרְעֹה שׁוֹם יוֹסֵף, גֻּבְרָא דְּמִטַּמְרָן גָּלְיָן לֵיהּ, וִיהַב לֵיהּ יָת אָסְנַת בַּת פּוֹטִי פֶרַע רַבָּא דְּאוֹן, לְאִתּוּ; וּנְפַק יוֹסֵף, שַׁלִּיט עַל אַרְעָא דְּמִצְרָיִם.

that is, "a man to whom secrets are revealed". This would seem to be guesswork. Paneach is a hapax legomenon, a word which does not appear elsewhere in Scriptures. And so, we must make an educated guess, on the basis of context. Consider the previous pasuk,

39. Then Pharaoh said to Joseph, "Since God has let you know all this, there is no one as understanding and wise as you.

לט. וַיֹּאמֶר פַּרְעֹה אֶל יוֹסֵף אַחֲרֵי הוֹדִיעַ אֱ־לֹהִים אוֹתְךָ אֶת כָּל זֹאת אֵין נָבוֹן וְחָכָם כָּמוֹךָ:

and the fact that he was appointed to this position of power because he was so wise and understanding, knowing the hidden meaning of Pharoah's dream, and this becomes a possibility. Add to this that we seem to know the word Tzofnas; it could mean tzafun, or something hidden. Combine the context with this knowledge and it is, indeed, a pretty good guess.

If we look to Midrash Rabba, it seems that this is what is guiding them. There is a machlokes about the meaning of Tzofnas Paneach:

ויקרא פרעה שם יוסף צפנת פענח אמר רבי יוחנן:
צפונות מופיע ונחות לו לאמרם.

רבי חזקיה אמר:
צפונות מופיע בדעת, מניח רוחן של בריות בהן.

ורבנן אמרי:
צד"י צופה
פ"א פודה
נו"ן נביא
תי"ו תומיך
פ"א פותר
עיי"ן ערום
נו"ן נבון
חי"ת חוזה

אמר רבי אחא:
צפונה אחת, שיש כאן באת לגלות עליה, שאת בנה בכולן, כתיב: (בראשית לג) ותגשן השפחות ותגש גם לאה וגו'. וביוסף כתיב: ואחר נגש יוסף ורחל.
אמר יוסף: הרשע הזה עינו רמה וכו'.
אמר הקב"ה: אתה הצנעת לאמך מן העין והגבהת עצמך, אני פורע לך ומגביהן, ויוסף בן שלושים שנה.

Thus, they spot the plausible meaning of tzefunah, but do dispute what the name means. The Rabanan even make it into a notrikon!

Ibn Caspi, a pashtan and rationalist, writes as follows:

Thus, it means "revealer of hidden things", and one shouldn't complain that this meaning for Paneach is not found elsewhere in Scriptures, for via our sins and the sins of our ancestors, we have lost perfect knowledge of our languages, as the Rambam explains in Moreh Nevuchim and in his commentary on the Mishnah upon the root taram.

My take on this is that of course language changes over time, and given that this is a hapax legomenon, we are forced to take a guess. But the question is whether the meaning of Tzofnas Paneach was something transmitted to, and through Chazal, as a matter of tradition, or whether this meaning was deduced through logical reasoning. For there is a danger that in saying that we don't know all the rules of ancient Hebrew, we open the door to any possible explanation, and thus chuck out even the rules we do know. See, for example, how this claim was advanced in the case of Arami Oved Avi, to pronounce the derasha as popularized the Haggada as peshat, using quite speculative (meaning made-up) grammatical rules, and the claim was then used to criticize Radak for rejecting it as derash, though he himself had said (elsewhere) that we have lost some of the rules of Hebrew grammar.

In the present case, I think this is overreach. There are at least three good reasons to believe that the name Tzofnat Paneach is Egyptian, rather than Hebrew.

1. Paneach is clearly a quadriliteral root (having four root letters) where Hebrew typically has triliteral roots.
2. Paneach has a peh, an ayin, and a chet. These are letters we might expect for an Egyptian name. (In terms of peh and ayin, think Poti-Fera and Pharaoh.)
3. It is a name given Yosef by an Egyptian king. Why would he rename him with a Semitic name.

Perhaps the coup de grâce is that Tzofnat Paneach does have meaning in ancient Egyptian (and I would stress ancient, which they were presumably not speaking when Ibn Caspi arrived in Egypt). It means "Sustainer Provider". This fits remarkably well with the context, for by interpreting this dream and giving this advice, and even more so, by his new role in taxing Egypt to sustain them in the years of famine, Yosef is indeed a Sustainer / Provider.

Update: Thanks to S., who notes this source. See the comment section for what he thinks about it, though: