Dhaka, March 15 -- The "genocidal acts" a United Nations investigation said on Thursday that Israel had carried out in Gaza are the most serious crimes recognized by international law, but also the most difficult to prove.The term genocide - derived from the Greek word "genos," for race or tribe, and "cide" from the Latin for "to kill" - was coined in 1944 by Raphael Lemkin. A Polish Jew who had fled to the United States, he used it to describe the crimes committed by Nazi Germany during the Holocaust.It was used for the first time within a legal framework by an international military tribunal at Nuremberg to try Nazi leaders for their crimes in 1945. However, those accused were eventually convicted on charges of crimes against humanity.G...