"A sheet of paper printed on one side only. Broadsides were used soon after the beginning of printing for royal proclamations and official notices. They were later a vehicle for political agitation and the expression of opposition to authoritarian rule. They were even used for the dissemination of scaffold speeches by criminals on the point of execution.
Early in the 16th century poems and ballads were printed in this form in England, and black letter fount continued to be used long after the introduction of roman for books.
Broadsides are also known as broadsheets, single sheets, street-or-still-ballads, and black-letter ballads. The term broadside is now applied to a variety of large regular and special-fold sheets, printed on one or both sides. A broadside may also contain one job or a number of jobs."
If I had to create a broadside for today it would read:
"Reference Librarian Reprimanded for Snarky Comment on Blog. Supervisor Mulls Termination!"
Glaister's Glossary of the Book: Terms used in Papermaking, Printing, Bookbinding, and Publishing with notes on Illuminated Manuscripts and Private Presses. Los Angeles, CA: University of California Press, 1979. p. 73