The name Abraham in the Bible
Abraham is the famous arch-father of all believers (Romans 4:11, Galatians 3:7; spelled Αβρααμ, Abraam). God cuts the covenant with Abraham of which Jesus is the fulfillment (Genesis 15, Galatians 3:7, 16, 29). Prior to this covenant, Abraham's name was Abram (Genesis 17:5).
Abraham has at least nine sons but most famous are Ishmael (by Hagar) and Isaac (by Sarah). When Abraham's wife Sarah dies, he marries Keturah, who bears him an additional six sons (Genesis 25:1-2). Abraham also has at least two sons by concubines (Genesis 25:6).
Etymology of the name Abraham
The Abarim Publications Editorial Team looked on dozens of web sites and countless hard-copies and all but a few merrily report that the name Abraham comes from the Hebrew words ab and hamon and means Father Of A Multitude. That these two words contain no R, while the name Abraham does, seems not to bother anyone.
The verbal explanation of Genesis 17:5 is hard to trace etymologically, as the new element רהם (rhm) does not exist in Hebrew. Perhaps God is suggesting that something unique is happening to Abram. There are some other words in Hebrew that are used only once, and are often highly significant. The phrase "father (of) many nations" reads אב המון נוים (ab-hamon-goyim), and that doesn't sound like "Abraham" at all (as mentioned, no R).
Whatever the name Abraham may mean, it certainly is not a compound of ab and hamon and certainly does not mean Father Of A Multitude. The Jewish Encyclopedia merrily states that "The form 'Abraham' yields no sense in Hebrew," but that displays boldness of the other side of the spectrum. The change from Abram to Abraham is accompanied by the initiation of the covenant of which the Messiah is the final result. It's impossible to defend that God would link a sign of no sense to an event that profound.
The only change from Abram to Abraham is the addition of the letter he after the rosh, and, much to our amazement, we see the verb ברה (brh ; meaning to cut a covenant!) emerge in the heart of the new name.
But, though certainly pleasing to a poetic eye, this may be a long shot. And to shoot even longer: Perhaps the new name is now a compilation of the words אבר (abar), meaning to fly, from the root אבר (abr) that has to do with flying and the flight of birds, plus the word הם (hem), which is the third person plural independent nominative pronoun, or simply "they": Fly They Will! It's not mentioned anywhere in the Bible, but since God has wings (God has no body and thus also no wings, but He does have an attribute that anthropomorphized results in wings; Psalm 36:7) man made in His image should have wings too, or at least when we're done growing.
The word from the "many nations" part mentioned above, and which is favored by many, המון (hamon) denotes a multitude in the sense of a large, specifically noisy crowd. This word comes from the verb המה (hama), cry aloud, make noise. If the segment הם comes indeed from המה, it denotes massive noise much rather than simply a multitude.
BDB Theological Dictionary concludes a troublesome paragraph by quoting J. Halevy's Revenue des Etudes Juives, which states that אבר is in fact אביר (abir), meaning strong one, denoting strength or leadership in a man. And הם comes from המה, but is never used anywhere in Scriptures. And it means multitude...(?)
If the name had been אבירהמה it would have meant Chief Of A Multitude. But now that the name is אברהם it means Flight 'n Noise, or Fly They Will, with at the heart of it the letter he to claim Abraham as Hebrew arch father and forming the verb ברה (to cut a covenant) which states the reason for the name Abraham.