The term exorcism does not always refer to a solemn and official prayer of the Church to free a person possessed by the Devil. In general, the term refers to a prayer that "curbs the power of the Devil and prevents him from doing harm." It is meant to protect us from the danger St. Peter described in Scriptures, Your adversary the Devil, as a roaring lion, goes about seeking whom he may devour. (1 Pet. 5:8)
The following prayer, issued by Pope Leo XIII on May 18th 1890, may be said either by a priest or a simple layman as any approved prayer. It should be recited standing. Its use is recommended whenever action of the Devil is suspected, spiritually or physically harming someone, causing violent temptations, storms or other calamities.