The phrase "in peril" conveys a state of danger or vulnerability. Alternative expressions could include "at risk", "in jeopardy", "in danger", "vulnerable", "endangered", "threatened", "compromised", "exposed", "off balance", "on the brink", "on the edge", "precarious", "unsafe" or "uncertain". All of these words represent a similar sense of potential harm or danger, and can be used interchangeably with "in peril" in certain contexts. Depending on the specific situation or context in which the word is being used, different synonyms may be more appropriate to convey the appropriate sense of danger or vulnerability.