E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Printed matter spread over an entire sheet of paper. The whole must be in one type and one measure, i.e. must not be divided into columns. A folio is when the sheet is folded, in which case a page occupies only half the sheet.
Pamphlets and broadsides were scattered right and left.Fiske: American History, chap. vii. p. 341.
In naval language, a broadside means the whole side of a ship; and to open a broadside on the enemy is to discharge all the guns on one side at the same moment.