From a derivative of muo (to shut the mouth); a secret or "mystery" (through the idea of silence imposed by initiation into religious rites) -- mystery.

1. a hidden or secret thing, not obvious to the understanding: 1 Corinthians 13:2; 1 Corinthians 14:2; (of the secret rites of the Gentiles, Wis. 14:15, 23).

2. a hidden purpose or counsel; secret will: of men, τοῦ βασιλέως, Tobit 12:7, 11; τῆς βουλῆς αὐτοῦ, Judith 2:2; of God: μυστήρια Θεοῦ, the secret counsels which govern God in dealing with the righteous, which are hidden from ungodly and wicked men but plain to the godly, Wis. 2:22. In the N. T., God's plan of providing salvation for men through Christ, which was once hidden but now is revealed: Romans 16:25; 1 Corinthians 2:7 (on this see ἐν, I. 5 f.); Ephesians 3:9; Colossians 1:26f; with τοῦ θελήματος αὐτοῦ added, Ephesians 1:9; τοῦ Θεοῦ, which God formed, Colossians 2:2; (1 Corinthians 2:1 WH text); τοῦ Χριστοῦ, respecting Christ, Colossians 4:3; τοῦ εὐαγγελίου, which is contained and announced in the gospel, Ephesians 6:19; ἐτελέσθη τό μυστήριον τοῦ Θεοῦ, said of the consummation of this purpose, to be looked for when Christ returns, Revelation 10:7; τά μυστήρια τῆς βασιλείας τῶν οὐρανῶν or τοῦ Θεοῦ, the secret purposes relative to the kingdom of God, Matthew 13:11; Mark 4:11; Luke 8:10; used of certain single events decreed by God having reference to his kingdom or the salvation of men, Romans 11:25; 1 Corinthians 15:51; of God's purpose to bless the Gentiles also with salvation through Christ (cf. Lightfoot on Colossians 1:26), Ephesians 3:3, cf. Ephesians 3:5; with τοῦ Χριστοῦ added, Ephesians 3:4; οἰκονόμοι μυστηρίων Θεοῦ, the stewards of God's mysteries, i. e. those intrusted with the announcement of God's secret purposes to men, 1 Corinthians 4:1; used generally, of Christian truth as hidden from ungodly men: with the addition of τῆς πίστεως, τῆς εὐσεβείας, which faith and godliness embrace and keep, 1 Timothy 3:9, 16; τό μυστήριον τῆς ἀνομίας the mystery of lawlessness, the secret purpose formed by lawlessness, seems to be a tacit antithesis to God's saving purpose, 2 Thessalonians 2:7.

3. Like רָזָא and סוד in rabbinic writers, it denotes the mystic or hidden sense: of an O. T. saying, Ephesians 5:32; of a name, Revelation 17:5; of an image or form seen in a vision, Revelation 1:20; Revelation 17:5; of a dream, (Theod.) Daniel 2:18f, 27-30, where the Sept. so renders רָז. (The Vulg. translates the wordsacramentum in Daniel 2:18; Daniel 4:6; Tobit 12:7; Wis. 2:22; Ephesians 1:9; Ephesians 3:3, 9; Ephesians 5:32; 1 Timothy 3:16; Revelation 1:20.) (On the distinctive N. T. use of the word cf. Campbell, Dissertations on the Gospels. diss. ix. part i.; Kendrick in B. D. American edition under the word ; Lightfoot on Colossians 1:26.)