English
flash rob
Blend of flash mob + rob.
Proto-Indo-European *Hrewp- ‘to snatch’
…
Frankish *raubōn
Late Latin raubō
Anglo-Norman rober
Middle English robben ‘to steal, rob’
English rob
Today it means
noun A form of organized theft in which a group of people enter a shop en masse and steal merchandise, while the employees are overwhelmed by sheer numbers.
Language periods are conventional ranges, not dates for this word.
Etymograph / flash rob