yellow rain

noun

: a yellow substance that has occurred in southeastern Asia as a mist or as spots on rocks and vegetation and has been held to be a biological warfare agent used in the Vietnam War but appears upon scientific examination to be identical to pollen-laden bee feces

Word History

First Known Use

1981, in the meaning defined above

Medical Definition

yellow rain

noun

-ˈrān 

: a yellow substance that has occurred in southeastern Asia as a mist or as spots on rocks and vegetation and has been held to be a biological warfare agent used in the Vietnam War but appears upon scientific examination to be identical to the pollen-laden feces of bees