Deu_2:20. A giant race identified with the Zuzim of Gen_14:5. Then "Ham" would be the chief city of the Zuzim and the root derivation of Ammon's capital, Rubbath Ammon. They dwelt where Ammon, having dislodged them, afterward dwelt when Israel invaded Canaan. E. of the modern rich and undulating Belka, from whence the Amorites expelled Moab. Zamzummims was the Ammonite name for the Rephaim, N.E. of Jordan, Peraea; the Rephaim once extended S.W. as far as the valley of the Rephaim near Hinnom and Bethlehem, S. of Jerusalem.
Fausset's Bible Dictionary
By Andrew Robert Fausset, co-Author of Jamieson, Fausset and Brown's 1888.
Zamzum?mims, a race of giants dwelling anciently in the territory afterwards occupied by the Ammonites, but extinct before the time of Moses (Deu_2:20).
The Popular Cyclopedia of Biblical Literature
by John Kitto.