*columbiad*

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. [ 1913 Webster ]

☞ 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. [ 1913 Webster ]