To secede means to formally break away from a larger group or organization. When a region, state, or group secedes, it declares that it no longer wants to be part of the larger entity it belonged to and wants to govern itself independently.

A famous example in American history occurred in 1860-1861, when eleven Southern states seceded from the United States to form the Confederate States of America. They believed they had the right to leave the Union, while President Lincoln and the Northern states argued that the Constitution didn't allow states to secede. This disagreement helped trigger the Civil War.

Countries and regions still debate secession today. Quebec has held votes on whether to secede from Canada. Scotland voted on seceding from the United Kingdom. These are serious political questions that affect millions of people.

When you secede, you're taking the step beyond disagreement to actually separating and going your own way. A related word is secession, which is the act of seceding. Someone who supports secession is called a secessionist.

Secession differs from ordinary disagreement. Students who disagree about playground rules aren't seceding. But if a group tried to split off and form their own separate school with its own principal and rules, that would be like secession.