Ad-i-ron'-dacks: The word means "tree-eaters," and was used by the Iroquis as an apithet of contempt and derision for their hereditary enemies, the Algonquins.Donaldson also quotes from a paper by Professor J. Dyneley Prince, entitled "Some Forgotten Indian Place-Names in the Adirondacks" published in the "Journal of American Folk-lore" for 1900, pp. 123-128. Here is a bit of it:
The mountainous district known as the Adirondacks takes its name from a well-known Mohawk word, ratirontaks, "they eat trees" or "those who eat trees". This term is in regular use at the present day among the Mohawks at Caughnawauga, P.Q., and elsewhere, to denote the so-called Algonquin tribe who formerly had their headquarters at Oka, not far from Montreal.Hope this is useful.