There are several synonyms for the word "renouncer," which means someone who gives up or relinquishes something. One alternative word is "abandoner," which refers to someone who deserts a particular cause, belief or person. Another option is "forsaker," which denotes someone who abandons or leaves behind something or someone. "Quitter" is another synonym for "renouncer," typically used to describe someone who gives up on a task or goal. "Refrainer" is also a synonym for "renouncer," often used to describe someone who abstains from a particular activity or behavior. In summary, there are several alternatives to "renouncer" when describing someone who gives up or relinquishes something.