Viaticum is a term used especially in the Catholic Church for the Eucharist (also called Holy Communion) administered, with or without Anointing of the Sick (also called Extreme Unction), to a person who is dying, and is thus a part of the Last Rites. According to Cardinal Javier Lozano Barragán, "The Catholic tradition of giving the Eucharist to the dying ensures that instead of dying alone they die with Christ who promises them eternal life."
The word viaticum is a Latin word meaning "provision for a journey," from via, or "way." For Communion as Viaticum, the Eucharist is given in the usual form, with the added words "May the Lord Jesus Christ protect you and lead you to eternal life". The Eucharist is seen as the ideal spiritual food to strengthen a dying person for the journey from this world to life after death.
Alternatively, viaticum can refer to an ancient Roman provision or allowance for traveling, originally of transportation and supplies, later of money, made to officials on public missions; mostly simply, the word, a haplology of viā tēcum ("with you on the way"), indicates money or necessities for any journey. Viaticum can also refer to the enlistment bonus received by a Roman legionary, auxiliary soldier or seaman in the Roman Imperial Navy.
The desire to have the bread and wine consecrated in the Eucharist available for the sick and dying led to the reservation of the Blessed Sacrament, a practice which has endured from the earliest days of the Christian Church. Saint Justin Martyr, writing less than fifty years after the death of Saint John the Apostle, mentions that “the deacons communicate each of those present, and carry away to the absent the consecrated Bread, and wine and water.” (Just. M. Apol. I. cap. lxv.)