"Saddlest" is a comparative form of the word "saddle," which means to sit on a horse's saddle or to put a saddle on a horse. Some synonyms for the word "saddlest" could include "most saddled," "heaviest saddled," or "firmly saddled." Other synonyms could include "burdened," "weighed down," or "loaded." These words suggest a heavy or cumbersome load, which could be used to describe an overloaded horse or a rider carrying too much weight. It's important to choose synonyms that accurately describe the situation in order to create a strong and effective piece of writing.