A widow is a person that has had their spouse die. So with that logic in mind, a widowmaker is something that kills ones spouse thus making said surviving spouse a widow. The CR500 and the KX500 have been called widowmakers since they were built. They are VERY powerful bikes and if you don't know what you are doing or if you don't respect their power you can get severely injured or killed. Hence the nickname of WIDOWMAKER.
Come on Kayla. That was an easy one.