Co*lum"bi*ad (?), n. [From
Columbia the United States.] (Mil.) A form of
seacoast cannon; a long, chambered gun designed for throwing shot
or shells with heavy charges of powder, at high angles of
elevation.
☞ Since the War of 1812 the Columbiad has been
much modified, especially by General Rodman, and the improved
form now used in seacoast defense is often called the Rodman
gun.