VOA慢速英语:Obama Appeals to UN in Effort Against IS Militants

atrocity – n. a very cruel or terrible act or action

behead – v. to cut off the head of (someone) especially as a punishment

conscience – n. the part of the mind that makes you aware of your actions as being either morally right or wrong

degrade – v. to cause (something complex) to break down into simple substances or parts

execute – v. to kill (someone) especially as punishment for a crime

horrific - adj.causing horror or shock