Commentary for Genesis 41:45

צפנת פענח signifies "Explainer of hidden things". There is no other example in Scripture of the word.

‘TZAPHNATH PA’NEI’ACH.’ Rabbi Abraham ibn Ezra said, “If this is an Egyptian word, we do not know its meaning, and if it is a translated one [from Yoseiph, the Hebrew name for Joseph], then we do not know the meaning of the name Yoseiph, [that is, the aspect of the name which has this translation].
But according to the opinion of earlier scholars, who say that it means “explainer of secrets” and is a Hebrew expression, it is possible that Pharaoh called him by this honorable name in accordance with the language of Joseph’s country after he asked him,⁷⁶I.e., Pharaoh asked Joseph, “What is the expression, in the Canaanitish language, which means ‘one who reveals secrets?’” and Joseph told him, “It is tzaphnath pa’nei’ach.” or the king may have known the language of Canaan, which was adjacent to Egypt, and its purport is that “he reveals concealed matters.” So also did Pharaoh’s daughter name Moses our teacher in the language of his people, for out of the water ‘m’shithihu’ (I pulled him).⁷⁷Exodus 2:10.
Now do not wonder why Egyptian writers called Moses, “Munyos,” for they changed the names into the language they understood or used, as the Targum Onkelos does in some cases, as for example, Between Kadesh and Shur,⁷⁸Above, 20:1. which he translated as “between Rekem and Chigra,” and similarly with many names. And in some places Onkelos does not change them at all, just as in the case of Sichon king of Cheshbon and Og king of Bashan, and many others like them. This is because in his times they were called thus in Aramaic.⁷⁹And therefore Onkelos wrote down the equivalent Aramaic name by which they were known in his time, which coincided with the way they were referred to in Scripture.

צפנת פענח, as translated by Onkelos, someone who reveals hidden things. It is a name taken from the Egyptian language. It was a common practice to link the name of a newly appointed official to his office in some manner. Moses changed the name of Joshua when he became selected to be one of the twelve spies. (Numbers 13,16) Similarly, Daniel, when appointed to high office by the king was renamed בל טשצר, (Daniel 1,6 and Daniel 4,5).