The word "rosest" is an archaic term used to describe the superlative form of the word "rose." However, there are several synonyms for the word "rosest" that convey a similar meaning. These include "best," "finest," "supreme," "ultimate," "optimal," "top-notch," "highest," "utmost," and "most superior." Each of these synonyms conveys a sense of excellence, superiority, and distinction, similar to the term "rosest." Whether describing the best quality of a rose or the top ranking in a competition, these synonyms effectively communicate the highest level of attainment.