flash mob

American  

[flash-mob] / ˈflæʃˌmɒb /

Or flashmob

noun

1. a group of people mobilized by social media to meet in a public place for the purpose of doing an unusual or entertaining activity of short duration.

   The flash mob brought wide smiles to the faces of commuters waiting for their train.

2. a group of teenagers who have contacted each other by cell phone and social media and gather in an area to trash it or to mug and beat passersby.

---

verb (used with object)

flash mobbed, flash mobbing

1. to crowd around (a place or person) in a flash mob.

   Dancing teenagers flash mobbed the store.

2. to commit violence against (a place or person) in a flash mob.

   The mayor imposed a curfew on all males under the age of 18 after two blocks of downtown Philadelphia were flash mobbed and severely damaged.

verb (used without object)

flash mobbed, flash mobbing

1. to organize or take part in a flash mob.

flash mob British  

noun

1. a group of people coordinated by email and social media to meet to perform some predetermined action at a particular place and time and then disperse quickly

---

Other Word Forms

• flash mobber noun
• flash mobster noun
• flashmobbing noun

Etymology

Origin of flash mob

2000–05; flash in the sense of ‘quick'; on the model of smart mob

Example Sentences

Cases have been brought over private Facebook messages, flash mob protests scattering anti-election leaflets, and vandalism of candidate placards.

From Barron's • Dec. 27, 2025

Michigan Attorney General Dana Nessel recently announced a series of arrests in flash mob thefts at Lululemon and Ulta locations.

From Washington Times • Jan. 1, 2024

A flash mob event is scheduled to take place at 15:30 GMT as part of a continued effort to save the building, on what would have been the opening day of the Coliseum's annual pantomime.

From BBC • Nov. 11, 2023

"They've also been known to do these flash mob style demonstrations and sometimes more coordinated demonstrations where they've shown up in places, like our nation's capital."

From Salon • Sep. 23, 2023

I mean, I don’t want to read too much into things, but wow: I meet a cute boy, and five seconds later, I’m in the middle of a flash mob marriage proposal?

From "What If It's Us" by Becky Albertalli and Adam Silvera