Ad populum
Etymology
Latin "argumentum ad populum" means an appeal "to the people." Its everyday nickname, the bandwagon fallacy, comes from the wagon that carried a band in nineteenth-century American parades; to "jump on the bandwagon" was to join a popular cause for the momentum. Both images point to the same slip: crowds as evidence.
noun phrase · /ad-POP-yuh-luhm/
Claiming something is true or right because most people believe it or do it.
What it names
Separates the popularity of a view from its accuracy, which can diverge completely.
Example
"Millions of users can’t be wrong" is ad populum — millions can be, and often have been.
Related idea
It overlaps with an appeal to authority, but the crowd, not the expert, is cast as the thing worth deferring to.