The word "counter-vailed" means to counterbalance or offset the effect of something. There are several synonyms for this word, including negate, nullify, annul, and cancel out. These words all refer to something that is opposing or reversing the effect of another thing. Another synonym for "counter-vailed" is "counteracted," which refers to the act of taking action to oppose or offset something. No matter which word you use to describe this concept, they all share the idea that something is being balanced or canceled out to prevent an effect from occurring. These synonyms are useful in both casual and academic contexts and can add depth and specificity to your writing.