1909 edition of Hasting's Dictionary of the Bible proposes that "Ham" is derived from Egyptian kem "black."
Dictionary of the Bible, ed. James Hastings (New York: Charles Scribner's Sons, 1909), 327
Ham.—The original (?) use of the name as =Egypt appears in Ps7854 10523. 27 10622. It has been derived from an Egyptian word kem, 'black,' in allusion to the dark soil of Egypt as compared with the desert sands (but see HAM [LAND OF]).