We were playing a Hallowe’en themed hangman game today and the Cub used “mummy”. I mentioned that “mummy” is an English word.
Then he asked, "Daddy, what did the Egyptians call ‘mummies’ ? "
I told him I did not know, but I would ask my imaginary internet friends. 
So, what was the word an ancient Egyptian would use to refer to a mummy?
The two words have no etymological connection.
Which two words? I think you were answering a different question than the OP was asking.
I know that. The Cub wants to know what the ancient Egyptians would have called a mummy.
According to this site, the word was “sah”. This site agrees, although it also uses the transcription “sahu” (most Semitic languages like Egyptian don’t write the vowels, so we don’t always know the exact pronunciation).
On the other hand, other sites like this one and this one say that “sah” was the name of the constellation of Orion. Perhaps this is a different word pronounced similarly.
–Mark
This link says it was “sah,” meaning “nobility” and “dignity.”
Ninja’d!
Thanks! I will tell the Cub.
Yes, “sah” - with a hard H. Not saaaaa, but sa(h!) (or possibly “sahoo.” Or in between: “sahuh.”)
Good question. I was years into Egyptology before I thought to ask it.
Mummy = mother, and mummy = preserved corpse.
Yeah, but no one was asking that question.
Well, “mut rukht” or "mut d’d’ " is motherf… never mind.
To be fair, it’s not exactly clear which English meaning of the word the OP was asking about. 
I’ll assume you’re kidding, because the only thing referenced was the english word for egyptian mummies. Nowhere was the British “mummy” or the English “mommy” mentioned.
Wait a second, “mommy” is English and “mummy” to refer to a mother is British? Then which is American?
No, I wasn’t kidding. I wouldn’t say the OP is insolubly ambiguous either; there are enough context clues to let somebody even from a non-US English speaking country (such as Canada, where I believe the OP is also from,) guess that he was talking about Egyptian dead mummies and not any word for a maternal parent. But he doesn’t define the word he’s talking about either, so I stand by it being “not completely clear.”
Seriously?
Yes.
See bolded. They used the word mummy to describe the ancient Egyptians bodies, reflected that mummy was an English word (as opposed to Egyptian), and the child asked what the word was in Egyptian.
I guess I have trouble with why anyone would think it was about the Britishism “mummy” for “mommy” (Americanism).
Seconded. The cub’s question is clearly about the Boris Karloff type… why would any kid wonder what Egyptians called their mothers?
Well, now I want to know!
I may be as dumb as a desiccated corpse, but I must confess that when I initially read the OP, I thought that the child had used the word “mummy” meaning “mother” (perhaps after watching too much Peppa Pig or something like that) and that NP had to explain that that usage was English (as in southern British, as opposed to American, not as in the common tongue that divides us; perhaps because the Scottish pronunciation is slightly different that what I heard in my head and what would most easily be confused with the word for a preserved corpse it didn’t strike me as wrong to use “English” that way). I thought the unrelated use had prompted the question about the Egyptian mummy in a random sort of word association way.
I almost immediately realized that it could have had the corpse meaning all along, but chalked it up as ambiguous. It wasn’t until I read the entire thread and went back and read the OP carefully that I realized that the corpse meaning was actually the more likely intention.