What is another word for backslider?
Pronunciation: [bˈaksla͡ɪdə] (IPA) 
Backslider is a term used for a person who goes back on their word or reverts to a previous state of behavior. Looking for synonyms for the term, you can use phrases like "renegade," "defector," "apostate," or "deserter." These words represent a person who has broken or renounced their allegiance or commitment to something or someone. Other alternatives to the term backslider include "traitor," "turncoat," or "rebel." Each of these words carries a slightly different meaning, but all refer to someone who has abandoned their previous position. Using any of these synonyms will help you to clearly convey the idea of someone who has gone back on their word.
