The key to Amos, Amasyah, Amasah, Amasai and Amshasai's names?

 At the end of ma'ariv on erev Simchat Torah, an idea popped into my mind: Was it possible that there was a connection between the name Amos and the Egyptian "mos" names? I vowed to bli neder check what names like Thutmose and Ahmose meant in Egyptian on motzei chag. Then I lucked out: A few pages into where I had left off in Werner Keller's The Bible As History, he wrote that the word Mos/Ms in Egyptian means son or teen.

Then something hit me. I remembered Rabbi Dr. Izaak Rapaport zt"l's essay on the Hebrew word "Shem".  In it he reached the conclusion that the word Shem originally meant "son" or "offspring".

In other words, yes, as Rabbi Ahron Marcus put it multiple times in Barzilai, this is a word that the Egyptians borrowed from paleo-Hebrew and flipped it. Shem/SM became MS!

That the Tribe of Yehudah in particular and Yisrael in general may have been influenced by Egyptian culture isn't such a big secret:

Egyptian influences on Yehudah:

* Bityah daughter of Pharaoh married Mared of Yehudah.

* King Shlomo married another daughter of Pharaoh.

* Sheshan, Sheshai and possibly Sheshbatzar are names that come from the Egyptian cloth Shesh.

* Sheshan had an Egyptian slave named Yarcha whom he later freed and married his daughter Achlai to him.

* Nachshon, Nachash (Yishai) and Saraf may be based on the snake, a symbol of Egypt.

* Pharaoh Shishak invaded Judea in the days of  Rechav'am. A dominant culture can greatly influence the weaker culture.

Additionally, three of this post's title names are of people from Yehudah:

Amos (according to Rabbi Marcus), Amasyah and Amasah.

While in Hebrew the various names are spelled quite differently - עמוס, עמשא, עמשי, עמסיה, עמשסי, Rabbi Marcus explains in detail in Barzilai how differences such as these simply point out to linguistic variants that developed in different parts of Eretz Yisrael and during different eras. The letter Sin is often a variant of Samech. In my opinion, all five names mean basically the same thing: The word "Am" (nation) merged with MS (child) =  in modern Hebrew this would be Am-Ben or "nation [that is a] son". Amasai and Amshasai add a bit of a twist in the pluralization of this term, making it Am-Banai, "nation [that is] my children". Amasyah provides a different twist by adding the theophoric y-h, making it Am-Ben-Y"H, "nation [that is] son of Hashem".  It's possible that Amasah means the same thing, as the sofit (ending letter) Alef  often serves to replace the theophoric sofit Y"H or YH"U, as is the case in עזרא and עזריה (Ezra and Azaryah).

The linguistic development of the names is also interesting to look at: In the earlier generations we had Amasah and Amasai. A little later, Amasyah. Several generations later, Amos. Finally, a few generations later, Amshasai.

In Hebrew, the chronological order would be:

עמשי

עמשא, עמשי (the two names were in use in the same generation)

עמסיה

עמוס

עמשסי

The name went from having a Sin and being plural to having an Alef at the end (quite possibly as secular Y"H variant) which makes it singular, to a clear theophoric singular with a Samech to a non-theophoric singular with a Samech to having a Shin and a Samech and going back to plural. Presumably, the last one evolved because of Babylonian or Persian influences during the Babylonian Exile (think words and names like Achashteranim, Artachshasta).