"Gweilo" is a Cantonese term meaning “White Devil”. Used as an insulting slang term for non-Asian humans in the former Eastern Bloc worlds and sometimes on New Tokyo. Also transliterated sometimes as "quailoh". See also Hung Mao and Gaijin.
In the Season Eight Alternate Timeline, Gweilo was what Asian-descended humans called non-Asians when they wanted to be nastier than simply using "Gaijin".