1. In the Old Testament (Hebrew)
2. In the New Testament
3. In the Septuagint
1. In the Old Testament
2. In the Apocrypha
3. In the New Testament

I. Terms.
1. In the Old Testament (Hebrew):
Tumah, "uncleanness," "defilement," occurs 26 times (Lev 7:20,21; 14:19; 15:3,15,26,30,31, etc.). niddah, "separation," "impurity," occurs in Lev 20:21; Ezr 9:11; Zec 13:1. erwah, occurs in Dt 23:14. erwath dabhar, "unclean thing" (Dt 24:1) is translated "uncleanness" in the King James Version. The adjective Tame, "defiled," "unclean," occurs 72 times (over half in Leviticus), but is never translated "uncleanness," but always "unclean." The verb Tame, "to make" or "declare unclean," occurs often. Other Hebrew verbs "to defile" are gaal, chalal, chaneph, Tanaph, `alal, `anah.
2. In the New Testament:
The Greek word for "uncleanness" is akatharsia, which occurs 10 times (Mt 23:27; Rom 1:24; 6:19; 2 Cor 12:21, etc.). miasmos, "pollution," occurs only in 2 Pet 2:10. The adjective akathartos, "unclean," occurs 31 times, 23 times in reference to unclean spirits (Luke once using the expression "unclean demon," 4:33), 4 times to ceremonial uncleanness (thee by Peter and one by John the revelator), and 4 times to moral uncleanness (three by Paul and one by John the revelator). Koinos, "common," "unclean," occurs 8 times in the sense of "unclean" (Mk 7:2,5; Acts 10:14,28; 11:8; Rom 14:14; Rev 21:27). The verb koinoo, "to defile," occurs 11 times (Mt 15:11,18,20; Mk 7:15, etc.). miaino, "to defile," occurs 5 times (Jn 18:28; Tit 1:15; Heb 12:15; Jude 1:8). moluno, "to make filthy," occurs 3 times (1 Cor 8:7; Rev 3:4; 14:4). spiloo, occurs twice (Jas 3:6; Jude 1:23) and phtheiro, "to corrupt," occurs 7 times in Greek, once in English Versions of the Bible (1 Cor 3:17).
3. In the Septuagint:
Akatharsia, "uncleanness," occurs 59 times in Septuagint (including many instances in apocryphal books) (1 and 2 Esdras, Tobit, 1 and 2 Maccabees, etc.). Akathartos, "unclean," occurs 134 times in the Septuagint (including one example in 1 Maccabees). Koinos, "unclean," and koinoo, "to make unclean," occur in Esther, Proverbs, Wisdom, 1, 2, 3 and 4 Maccabees). Miaino, "to defile," occurs over 100 times. Moluno, "to make filthy," occurs 18 times (both in the Old Testament and in the Apocrypha).
II. Possible Relation of Israels Laws on Uncleanness with the Laws of Taboo among the Nations:
W. R. Smith (Lectures on the Religion of the Semites, 152-55) thinks there is a kinship between Israels laws of uncleanness and the heathen taboo. Frazer, in The Golden Bough, shows numerous examples of the taboo among various tribes and nations which present striking similarity to some of Israels laws on uncleanness. But does this diminish our respect for the Old Testament laws on uncleanness? Might not Yahweh use this natural religious perception of men as to an intrinsic distinction between clean and unclean in training Israel to a realization of a higher conception--the real difference between sin and holiness, i.e. between moral defilement and moral purification? The hand of Yahweh is visible even in the development of Israels rudimentary laws on ceremonial uncleanness. They are not explicable on purely naturalistic grounds, but Yahweh is training a people to be holy, and so He starts on the lower plane of ceremonial uncleanness and cleanness (see Lev 11:44 as to the purpose of Yahweh in establishing these laws respecting clean and unclean animals).
III. Teaching as to Uncleanness.
1. In the Old Testament:
Each term above for uncleanness is used in two senses: (a) to signify ceremonial uncleanness, which is the most usual significance of the term in the Old Testament; (b) but, in the Prophets, to emphasize moral, rather than ceremonial, uncleanness. There are four principal spheres of uncleanness in the Old Testament:
(1) Uncleanness in the Matter of Food.
The law as to clean and unclean beasts is laid down in Lev 11:1-23. Notice that the law does not extend to vegetable foods, as does a similar law in the Egyptian religion. Four kinds of beasts are named as fit for food: (a) among quadrupeds, those that both chew the cud and part the hoof; (b) among fishes, only those having both fins and scales; (c) most birds or fowls, except, in the main, birds of prey and those noted for uncleanness of habits, are permitted; (d) of insects those that have legs above the feet to leap withal (e.g. the cricket, the grasshopper, etc.), but those that go on all four, or have many feet, or go upon the belly (e.g. worms, snakes, lizards, etc.), are forbidden.
See, further, FOOD.
(2) Uncleanness Connected with the Functions of Reproduction (Leviticus 12 and 15).
In Lev 15:2-18, we find the laws applied to issues of men; in 15:19 ff, to the issues of women. Not only is the man or woman unclean because of the issue, whether normal or abnormal, but the bed on which they lie, or whatever or whoever is touched by them while they are in this state, is unclean. The uncleanness lasts seven days from the cessation of the issue. To become clean men must wash their clothes and batheir bodies (though this requirement is not made of women), and both men and women must offer through the priest a pair of turtle-doves, or two young pigeons (Lev 15). According to Lev 13, the woman who conceives and bears a child is unclean. This uncleanness lasts seven days if the child born is a male, but 14 days if the child is a female. However, there is a partial uncleanness of the mother that continues 40 days from the birth of a male, 80 days from the birth of a female, at the end of which period she is purified by offering a lamb and a young pigeon (or turtle-dove), or if too poor to offer a lamb she may substitute one of the birds for the lamb.
(3) Uncleanness Connected with Leprosy.
According to Lev 14 and 15, the leper was regarded as under the stroke of God, and so was deemed unclean. The leper (so adjudged by the priest) must separate himself from others, with torn clothes, disheveled hair, and crying with covered lips, "Unclean! Unclean!" That is, he was regarded as a dead man, and therefore unclean and so must live secluded from others.
See, further, LEPER, LEPROSY.
(4) Uncleanness Associated with Death.
According to Lev 15:24-40, anyone who touched a dead beast, whether unclean or clean, was rendered unclean. According to Nu 19:11-22, anyone touching the corpse of a human being is unclean. Likewise, everyone in the tent, or who enters the tent, where lies a dead man, is unclean seven days. Even the open vessels in the tent with a dead person are unclean seven days. Whoever, furthermore, touched a dead mans bone or grave was unclean seven days. Purification, in all these cases of uncleanness as related to death, was secured by sprinkling the ashes of a red heifer with living water upon the unclean person, or object, on the 3rd and 7th days.
2. In the Apocrypha:
In Tobit 3:7-9; 6:13,14; 7:11; 8:1-3; 1 Macc 1:41-53, and in other books, we find the same laws on uncleanness recognized by the descendants of Abraham. It was regarded as abominable to sacrifice other animals (swine for instance) than those prescribed by Yahweh. There is a growing sense in Israel during this period, that all customs and all conduct of the heathen are unclean. Witness the resistance of the loyal Jews to the demands of Antiochus Epiphanes (1 Macc 1; 2; 6; 7). The sense of ceremonial uncleanness was still a conspicuous element in the religious consciousness of the Jews in the inter-Biblical period. But the training of God in ceremonial purification and in the moral and spiritual teachings of the prophets had prepared the way for an advance in moral cleanness (both in thought and in practice).
3. In the New Testament:
By the days of Jesus the scribes and rabbis had wrought out a most cumbrous system of ceremonial uncleanness and purification. Nor did they claim that all their teachings on this subject were found in the Old Testament. See TRADITION. This is fitly illustrated in the New Testament in the washing of hands. See UNWASHEN. When the Mishna (the collection of rabbinic teachings) was produced, the largest book was devoted to the laws of purification, 30 chapters being used to describe the purification of vessels alone.
See Jn 2:1-11, and note how the Jews had six stone waterpots for purification at the wedding in Cana. See Jn 3:25 as to the controversy on purification between Johns disciples and the Jews. This question of cleanness and uncleanness was a tremendous issue with every Jew. He must keep himself ceremonially clean if he would be righteous and win the approval of God.
Jesus utterly disregarded for Himself these laws of purification, though He orders the cleansed leper to return to the priest and secure his certificate of cleansing. He did not wash His hands before eating, and His disciples followed His example. Therefore, the Pharisees challenged Him to give an account of His course and that of His disciples (Mt 15:3-20 = Mk 7:6-23). Jesus then enunciated the great principle that there is no ceremonial, but only moral and spiritual, uncleanness. Not what goes into a man from hands that touch unclean things defiles the man, but the things that come out of his heart, evil thoughts, hatred, adultery, murder, etc., these defile the man.
Paul likewise regarded nothing as unclean of itself (Rom 14:14,20; Tit 1:15), yet no man should violate the scruples of his own conscience or that of his brother (and thus put a stumblingblock in his way). Love, not ceremonialism is the supreme law of the Christian. Paul, in submitting to the vow of purification in Jerusalem, set an example of this principle (Acts 21:26).

W. R. Smith, Lectures on the Religion of the Semites (especially pp. 152-55, on taboo, and pp. 455, 456, on the uncleanness of sexual intercourse); Frazer, The Golden Bough (examples of taboo and similar laws and customs among various nations); Frazer, article "Taboo" in Encyclopedia Britannica, 9th edition; Benzinger, Hebrew Archaeology; Nowack, Hebrew Archaeology; Kellogg, commentary on "Leviticus" (Expositors Bible); Kalisch, Leviticus; Dillmann-Ryssel, Leviticus; Schultz, Dillmann, Smend, Marti, Davidson, in their Old Testament Theologies, give useful hints on this subject; article "Casuistry" (Hebrew) in ERE, III, is valuable.
Charles B. Williams