There are several synonyms for the phrase "measurement by eye," including "eyeballing," "visual estimation," "rough measurement," and "approximate measurement." These terms all refer to the practice of assessing size or distance without the aid of a tool or instrument. While measurement by eye can be useful in certain circumstances, it is generally less accurate than using a ruler, tape measure, or similar device. Therefore, it is important to keep in mind the limitations of visual estimation and use it only when needed and appropriate. In situations where precision is necessary, relying solely on measurement by eye may result in errors or mistakes.