Princeton's WordNet

1. krypton, Kr, atomic number 36(noun)

   a colorless element that is one of the six inert gasses; occurs in trace amounts in air

2. Khmer Rouge, KR, Party of Democratic Kampuchea, Communist Party of Kampuchea(noun)

   a communist organization formed in Cambodia in 1970; became a terrorist organization in 1975 when it captured Phnom Penh and created a government that killed an estimated three million people; was defeated by Vietnamese troops but remained active until 1999