noun

defection

dih-FEK-shun/dɪˈfekʃn/

The act of abandoning allegiance to a country, group, or cause.

The soldier’s defection takes him from his old camp to the opposing side.

An adult in a plain blue uniform leaving a blue group's camp to join a distant red group's camp, hands empty, allegiance change, no flags.

Etymology

deLatindown, away

+fectLatindo, make

+ionLatinaction

“Do, make” combined with “away” underlies a Latin verb meaning “fail” or “desert.” The noun moved from failure in duty to abandoning allegiance to a party, leader, or cause.

In context

Kings and Generals54:02

However, three years later, Churchill’s allegiances shifted to William of Orange, and his defection to William’s cause was one of the decisive factors in the success of the Glorious Revolution.

War of the Spanish Succession: All Battles and Events - FULL DOCUMENTARY

More examples

Several defections weaken the ruling party.
The report follows his defection to the opposing side.
She explains the reasons for her defection from the movement.

Forms

defection · defections

defect verb — abandon one allegiance for another

Similar words

desertion: Desertion abandons a duty or position; defection especially involves abandoning allegiance to a group or cause.
betrayal: Betrayal violates trust; defection specifically abandons an allegiance.