Josh Waxman , Parsha Blog, june 22, 2009,
There is a desire to know more about our favorite Biblical characters, and to know more about names we hear over and over, but it might just not be possible. I don't recall any midrashim telling of any great deeds of Nun.
We can try to analyze Nun's name, however. Here's where we have some fun with speculation.
Nun in Aramaic and other Semitic languages means fish. But it means something different, though related, in Egyptian. It is the name of the watery abyss,
In Egyptian mythology, Nu is the deification of the primordial watery abyss. In the Ogdoadcosmogony, the name nu means "abyss".
Nu, being a concept, was viewed as not having a gender, but also had aspects that could be represented as female or male as with most Egyptian deities. Naunet (also spelt Nunet) is the female aspect, which is the name Nu with a female gender ending. The male aspect, Nun, is displayed with a male gender ending. As with the other three four primordial concepts of the Ogdoad, Nu's male aspect was depicted as a frog, or a frog-headed man. In Ancient Egyptian art, Nun also appears as a beardedman, with blue-green skin, representing water. Naunet is represented as a snake or snake-headed woman.
Interestingly, Hoshea bin Nun could be taken similarly to Moshe: he was saved from the watery abyss.
Or we can take it as the name of an Egyptian deity. There are other Israelites with names suggesting Egyptian deities, not just Nun. I'm thinking of Achira ben Ainan. Since Hoshea is the equivalent of the theophoric name Yeho-shua, perhaps there was some Egyptian deity originally tacked on to Hoshea's name, and that is why Moshe took pains to name him Yehoshua.