Accident or casus, as distinguished from dolus and culpa, and hence relieving one from the duty of performing an obligation(noun)
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Use "periculum" in a sentence
"Fuerunt alii similis amentiae, cives Romani — — Multi enim omnis aetatis, omnis ordinis, utriusque sexus, etiam vocuntur in periculum et vocabuntur.] 189 Tertullian ad Scapulum."
"Indeed Ubi periculum took its cue from the events in Viterbo to prescribe a particularly tough dietary regimen for the conclave."
"After his election Gregory X set out some hard-line regulations for future elections: his 1274 constitution Ubi periculum contains the first use of the word conclave—from the Latin cum clavis, “with a key.”"