"Peers out" is a commonly-used expression that refers to the act of looking out of a window or door. However, there are several synonyms that can be used instead of this phrase. For example, "gazes out" is similar to "peers out" but implies a more intentional and prolonged act of looking. "Looks out" is a more straightforward synonym that conveys the same idea without the nuance. "Scans" or "scrutinizes" can be used to imply a more focused and detailed examination of the surroundings. Finally, "glances out" is a synonym that can be used to indicate a quick and casual look through a window or door.