The most common name for the American Civil War in modern American usage is simply "The Civil War". Although rarely used during the war, the term "War Between the States" became widespread afterward in the Southern United States. During and immediately after the war, Northern historians often used the terms "War of the Rebellion" and "Great Rebellion", and the Confederate term was "War for Southern Independence", which regained some currency in the 20th century but has again fallen out of use. The name "Slaveholders' Rebellion" was used by Frederick Douglass and appears in newspaper articles. "Freedom War" is used to celebrate the war's effect of ending slavery.

During the Jim Crow era of the 1950s, the term "War of Northern Aggression" developed under the Lost Cause of the Confederacy movement by Southern historical revisionists or negationists. This label was coined by segregationists in an effort to equate contemporary efforts to end segregation with 19th-century efforts to abolish slavery.

Several names also exist for the forces on each side; the opposing forces named battles differently as well. The Union forces frequently named battles for bodies of water that were prominent on or near the battlefield, but Confederates most often used the name of the nearest town. As a result, many battles have two or more names that have had varying use, but with some notable exceptions, one name has eventually tended to take precedence.