Finding suitable synonyms for "pass out of sight" depends on the context of the statement. Depending on the context, these could include "disappear," "evaporate," "vanish," or "fade away." Other possibilities might include "slip away," "become obscured," or "disappear from view." The term "disappear" is likely the most frequently used synonym for "pass out of sight," as it effectively communicates the idea of something or someone no longer being visible. Different words may be appropriate depending on whether the context involves a physical object, a person, or a metaphorical concept. Regardless, the goal is always to convey the idea that something or someone has left the observer's perception.