slang A non-Japanese person with a very strong, perhaps obsessive, interest in Japanese culture and media. The term gained popularity on the forum 4chan. Often used as a term of derision. Not every manga fan is a weeaboo, OK?
More extreme fans became branded as Japanophiles, Wapanese ("Wannabe Japanese"), or Weeaboos (slang for Wapanese) in the same derogatory fashion as fans of Star Trek had been branded "Trekkies." Both fan groups have now claimed these derogatory terms as their own positive names for themselves.