hoosier

What it means

1. A native or resident of the U.S. state of Indiana.

   Indiana’s Borderlanders called themselves Hoosiers, came from the backcountry of Kentucky and western Virginia, and were ambivalent about slavery.

   2011, Colin Woodard, chapter 16, in American nations, New York: Penguin, →ISBN

   Synonyms: Indianan

2. Someone associated with Indiana University, for example as a student, alum, or sports team member, or as a fan. This is also the university's sports mascot.
3. slangSt. Louis; Missouri; formerly Southern US; St. Louis; Missouri; formerly Southern USAn uneducated, tasteless, boorish white person.

   Near-synonym: (Canada) hoser

   2 more examples

   "The mall? Belinda, mall pickups are for hoosiers," I say, St. Louis slang for white trash. "With femullets." [...] "But Jake's no hoosier."

   2014, Emily Giffin, The Emily Giffin Collection: Volume 2: Baby Proof, →ISBN

   Taken as a whole, the article portrayed Ray as an indigent, racist “Hoosier” (St. Louis slang for redneck) with an inept, habitual tendency to commit petty crimes.

   [2015, Pate McMichael, Klandestine: How a Klan Lawyer and a Checkbook Journalist ..., page 2

   Synonyms: white trash, hoser

In a sentence

Indiana’s Borderlanders called themselves Hoosiers, came from the backcountry of Kentucky and western Virginia, and were ambivalent about slavery.

2011, Colin Woodard, chapter 16, in American nations, New York: Penguin, →ISBN

Where it comes from

Uncertain. See Wikipedia's article on the subject for theories. Popularized by the 1830 John Finley poem “The Hoosier’s Nest”.