The phrase "most outstretching" refers to something that reaches the furthest or stretches the longest. Some synonyms for this phrase include "far-reaching," "extensive," "expansive," "spacious," "prolonged," "stretched out," "elongated," "lengthy," "extended," "sweeping," and "broad." They all convey a sense of something that extends beyond usual limits and covers a wide area, both physically and figuratively. "Most outstretching" can be used to describe physical objects, ideas, or concepts, and implies a sense of grand scale and significance. The use of synonyms can enrich language and provide a wider range of expression.