The term "contradicter" refers to someone who contradicts or opposes another's opinion or statement. There are several synonyms to describe this type of behavior, including "debater," "skeptic," "dissentient," "disputant," "challenger," and "opponer." A debater is someone who is skilled in argument and strives to prove their point, while a skeptic is someone who doubts or questions the validity of a given idea. A dissentient is someone who opposes an established belief or tradition, and a disputant is someone who actively engages in arguments or disagreements. A challenger is someone who challenges the validity or truth of a particular assertion, while an opponer is someone who actively opposes or contests an idea or claim.