Mierny is a Polish word that translates to "moderate" or "mediocre" in English. When looking for synonyms for this word, some options include "average," "ordinary," "so-so," "fair," "middling," "modest," "unexceptional," "tolerable," and "adequate." Each of these words conveys a similar meaning to mierny -- something that is not outstanding, but also not terrible. It's important to consider the context in which this word is being used, as different synonyms may be more appropriate depending on the situation. Overall, the synonyms for mierny offer a range of options to describe something that is average or unremarkable.