MDK Share definition Flag MDK, a term commonly used in the RAF to shorten 'Murder Death Kill'. Used in a jokingly way to describe a gorey end. 1. Whoa, he flew straight into a wall. Much MDK! 2. Zoom swish boom <MDK!!!> MDK by Dan0kun September 3, 2005 0 0 Get merch Get the MDK mug. Buy Now — $32.95 See more merch