noun
plural -ils
somewhat formal + literary
[noncount] :the possibility that you will be hurt or killed or that something unpleasant or bad will happen :danger
usually used in the phrase in peril
[count] :something that is likely to cause injury, pain, harm, or loss :danger
usually plural
at your (own) peril
used to say that if you do something you should be aware that it is dangerous and that you could be harmed, injured, punished, etc.