The flâneur is often contrasted with the badaud; while both terms are applied to urban wanderers and observers, badaud has connotations of ignorance and idle curiosity. A flâneur studies a city as if it were a good, thought-provoking book; a badaud thoughtlessly gawps at it as if it were a vapid TV show.
Flâneur comes from the French word flâner, meaning “to stroll.” The related term flânerie describes “the disposition or practice of an idler or lounger.” (Thanks, OED!) Baduad is also French in origin and does not appear to have crossed over into English. It means “gawker” or simply “bystander.” Badauderie refers to the act of gathering into a crowd on the street in order to gape at something.
I find it amusing that while English has an analogous term for badaud (rubbernecker), it is most often applied to people who take a morbid interest in car wrecks —- the cause of “onlooker delays,” as my local traffic reporter so delicately puts it. The French badaud might stop to watch someone attempt to regain control of a handful of balloons, or a dog walker pursue their unruly charge through a flock of geese, or something equally innocent and charming; the American rubbernecker just wants to see if there’s a corpse on the other side of that shattered windshield.