'Hiero' is not originally a Greek form, though it is commonly believed to be.  The earliest reference to this form is found on the famous Rosetta Stone trilingual inscription.  In the Greek portion of the inscription there is a reference made to the three languages of the inscriptions on the stone.  The languages mentioned are [ierois], [egkhohriois] ([kh] for the letter Khi and [oh] for Omega) and [ellehnikois grammasin] ("Ellanikois" which is "Greek") (reference: Budge, p.75).  The languages are listed in the order that they appear on the Rosetta Stone.  Egkhoriois is written in a late script style and is understood to be the language of the common people for that time.  Ierois refers to the language written in Hieroglyphic writing.  This is also the first known mention of a name of the language of Egypt.

     The name 'Ierois' is composed of [ier] and the Greek suffix [ois].  The Hebrew word for the Nile is simply the Hebrew spelling of the Egyptian word for the Nile, and it is spelled [YAR].  Similarly, [ier] is the Greek spelling of some Egyptian name.  Vowels usually do not translate well from Hebrew to Greek as you can see in my article on 'Biblical Orthographic Transliterations'.  The way to represent [Y] in Greek is by Iota [i].  It seems [ier] most likely refers to [YAR] "Nile".  If that is true then [ierois] would translate into English as "Nilotic".  This, of course, is not the same as the modern language called "Nilotic".  The modern language called "Nilotic" has been heavily Arabicised.  That language is called "Nilotic" because the people who speak that language live about part of the Nile.  This is significant because the same principle in naming was applied well over 2000 years ago, as in our time.  The naming process would be expected to be the same because in both cases we are talking about an indigenous people speaking a particular language and living by the Nile.

     We can be reasonable sure that the Greek spelling [ier] has come from Egyptian, as the Hebrew spelling [YAR] has come from Egyptian.  I think we could be certain if we could find [YAR] in Egyptian hieroglyphic writing.  For a long time I puzled over a curious hieroglyphic symbol.  It is only the forarm of a lion with the head of the lion.  It seems strange until we realize that it is simply a compound symbol.  The forearm is out in front and we read toward the face of the lion, so we can read [arm] [head].  But why the arm and head of a lion in particular ?  Because [lion] is also part of the compound symbol.  The [arm] is [Y] by the acrophonic principle because the word for "arm" is [YD] as in Ancient Hebrew.  The word for [lion] is [ARY] as in Ancient Hebrew, so we have [A].  The name of the [head] symbol is [RAS] as in Ancient Hebrew.  So we have the letters [Y] [A] [R] in that order by the acrophonic principle.  That particular compound symbol is the word [YAR] which means "Nile".  The Hebrew came from Egypt, so they would have used the Egyptian word for "Nile".

     We have discovered that [ier] has come from [YAR].  We have discovered that [YAR] can be found in Ancient Egyptian hieroglyphic writing.  We also know that [YAR] means "Nile" and that the word was in use in Egypt in Ancient times.  We have learned that [ierois] can be translated into English as "Nilotic".  "Hieroglyph" actually has a derivation from the sense of "Nile writing".

Budge, Wallis E. A., The Rosetta Stone, Dover, New York, 1989.