HOLY OIL. — The term, even in canon law (can. 1271), applies to vegetable, animal, or adulterated products having a resemblance to oil; but in the proper and canonical sense (can. 734 sqq., 781, 945 sqq.) it denotes the liquid pressed from ripe olives, consecrated for use as matter in certain Sacraments and in consecrations.
In literature, art, and religious symbolism, oil is often employed as a figure of abundance, joy, strength, suavity, fertility, and incorruptibility; it is also taken to signify certain realities of a supernatural order, namely grace, mercy, and the outpouring of the charisms of the Holy Spirit (Sum. Theol., 3, q. 72, a. 2 sqq.). For this reason, from antiquity it has been used in sacred worship, as in the consecration of altars, vessels, and places (Gen. 28:18; 35:14; Ex. 30:24 sqq.; 40:9 sqq.), of priests (ibid. 29:7 sqq.; Lev. 8:11), and of kings (1 Reg. 10:1; 16:13); in sacrifices and offerings of firstfruits (Lev. 2:1 sqq.; Deut. 14:23); and in the purification of lepers (Lev. 14). The Saviour is called “Christ” (the Anointed) by antonomasia. In the New Testament it is used to heal the sick, in Extreme Unction, mixed with spices to honor guests (Lk. 7:46; Jn. 11:2), in burial (ibid. 19:40; Mk. 16:1), etc.
Holy oil, distinct from oil for lamps (can. 1271; V. LAMPADA) and from that blessed for the use of the faithful (Rituale, tit. 8, cap. 19), is oil blessed with solemn rite by the bishop. Consecration is distinguished from blessing by the use of holy oil. There are three kinds of holy oil: 1) oil of the sick (oleum infirmorum): it is the matter of Extreme Unction and is also used to bless bells externally; 2) oil of catechumens (sanctum oleum, oleum catechumenorum): used in Baptism, for anointing the hands of the newly ordained priest, and for pouring into the baptismal font; 3) holy chrism (oil mixed with balsam): the matter of Confirmation, used in all consecrations, for pouring into the baptismal font, on the heads of the newly baptized and newly consecrated bishops, and also for anointing their hands.
Essential is the blessing, usually performed on Holy Thursday by the bishop; the Pope may probably delegate to a simple priest the faculty of blessing the chrism; he certainly may delegate the blessing of the oil of the sick (can. 945), a faculty ordinarily exercised by Eastern priests. For liceity it is required that holy oils be recent, i.e., of the current year; but in urgent cases old holy oils not corrupted may be used within four years (Collectanea S. C. Prop. Fide, nn. 183; 263; 1965, 3-4). In case of necessity, pure oil may be added in smaller quantity (can. 734); the operation may be repeated. They must be kept in church in a separate place, in sealed and well-closed vessels; if necessary they may be kept at home. The parish priest must promptly procure them from his own bishop; and this important act may be governed by various local norms. Transmission by mail or courier is excluded, though it is permitted by means of a trusted layperson (Collectanea cit., n. 2106).
In an improper sense, the term “holy oil” is also applied to a liquid, similar to oil, issuing from the tombs or relics of certain saints, also called “oleum martyris” (Paulinus of Nola, Carmen, 18, 38-48: PL 61, 491) or “manna” (Gregory of Tours, De miraculis, I, 30: PL 71, 934, e.g., of St Martin, St Nicholas of Bari).