Probably from a primary verb eiro (to join); peace (literally or figuratively); by implication, prosperity -- one, peace, quietness, rest, + set at one again.

1. a state of national tranquility; exemption from the rage and havoc of war: Revelation 6:4; πολλή εἰρήνη, Acts 24:2 (3); τά (WH text omits τά) πρός εἰρήνην, things that look toward peace, as an armistice, conditions for the restoration of peace Luke 14:32; αἰτεῖσθαι εἰρήνην, Acts 12:20; ἔχειν εἰρήνην, of the church free from persecutions, Acts 9:31.

2. peace between individuals, i. e. harmony, concord: Matthew 10:34; Luke 12:51; Acts 7:26; Romans 14:17; 1 Corinthians 7:15; Galatians 5:22; Ephesians 2:17; Ephesians 4:3; equivalent to the anthor of peace, Ephesians 2:14 (cf. Buttmann, 125 (109)); ἐν εἰρήνη, where harmony prevails, in a peaceful mind, James 3:18; ὁδός εἰρήνης, way leading to peace, a course of life promoting harmony, Romans 3:17 (from Isaiah 59:8); μετ' εἰρήνης, in a mild and friendly spirit, Hebrews 11:31; ποιεῖν εἰρήνην, to promote concord, James 3:18; to effect it, Ephesians 2:15; ζητεῖν, 1 Peter 3:11; διώκειν, 2 Timothy 2:22; with μετά πάντων added, Hebrews 12:14; τά τῆς εἰρήνης διώκειν, Romans 14:19 (cf. Buttmann, 95 (83); Winers Grammar, 109 (103f)). Specifically, good order, opposed to ἀκαταστασία, 1 Corinthians 14:33.

3. after the Hebrew שָׁלום, security, safety, prosperity, felicity, (because peace and harmony make and keep things safe and prosperous): Luke 19:42; Hebrews 7:2; εἰρήνη καί ἀσφάλεια, opposed to ὄλεθρος, 1 Thessalonians 5:3; ἐν εἰρήνη ἐστι τά ὑπάρχοντα, αὐτοῦ, his goods are secure from hostile attack, Luke 11:21; ὕπαγε εἰς εἰρήνην, Mark 5:34, and πορεύου εἰς εἰρήνην Luke 7:50; Luke 8:48, a formula of wishing well, blessing, addressed by the Hebrews to departing friends (לְשָׁלום לֵך 1 Samuel 1:17; 1 Samuel 20:42, etc.; properly, depart into a place or state of peace; (cf. Buttmann, 184 (160))); πορεύεσθαι ἐν εἰρήνη, Acts 16:36, and ὑπάγετε ἐν εἰρήνη, James 2:16, go in peace, i. e. may happiness attend you; ἀπολύειν τινα μετ' εἰρήνης, to dismiss one with good wishes, Acts 15:33; ἐν εἰρήνη, with my wish fulfilled, and therefore happy, Luke 2:29 (see ἀπολύω, 2 a.); προπέμπειν τινα ἐν εἰρήνη free from danger, safe, 1 Corinthians 16:11 (others take it of inward peace or of harmony; cf. Meyer at the passage). The Hebrews in invoking blessings on a man called out לְך שָׁלום (Judges 6:23; Daniel 10:19); from this is to be derived the explanation of those expressions which refer apparently to the Messianic blessings (see 4 below): εἰρήνη τῷ οἴκῳ τούτῳ, let peace, blessedness, come to this household, Luke 10:5; υἱός εἰρήνης, worthy of peace (cf. Winers Grammar, § 34, 3 N. 2; Buttmann, 161f (141)), Luke 10:6; ἐλθέτω ἡ εἰρήνη ἐπ' αὐτόν, let the peace which ye wish it come upon it, i. e. be its lot, Matthew 10:13; to the same purport ἐπαναπαήσεται ἡ εἰρήνη ὑμῶν ἐπ' αὐτόν, Luke 10:6; ἡ εἰρήνη ὑμῶν πρός ὑμᾶς ἐπιστραφήτω, let your peace return to you, because it could not rest upon it, i. e. let it be just as if ye had not uttered the wish, Matthew 10:13.

4. Specifically, the Messiah's peace: Luke 2:14; ὁδός εἰρήνης, the way that leads to peace (salvation), Luke 1:79; εἰρήνης ἐν οὐρανῷ, peace, salvation, is prepared for us in heaven, Luke 19:38; εὐαγγελίζεσθαι εἰρήνην, Acts 10:36.

5. according to a conception distinctly peculiar to Christianity, "the tranquil state of a soul assured of its salvation through Christ, and so fearing nothing from God and content with its earthly lot, of whatsoerer sort that is": Romans 8:6; ἐν εἰρήνη namely, ὄντες; is used of those who, assured of salvation, tranquilly await the return of Christ and the transformation of all things which will accompany that event, 2 Peter 3:14; (πληροῦν πάσης ... εἰρήνης ἐν τῷ πιστεύειν, Romans 15:13 (where L marginal reading ἐν πιστεύειν εἰρήνη)); ἔχειν ἐν Χριστῷ εἰρήνην (opposed to ἐν τῷ κόσμῳ θλῖψιν ἔχειν), John 16:33; ἔχειν εἰρήνην πρός τόν Θεόν, with God, Romans 5:1, (εἰρήνη πρός τινα, Plato, rep. 5, p. 465 b.; cf. Diodorus 21, 12; cf. Meyer on Romans, the passage cited; Winer's Grammar, 186 (175); 406 (379))); εὐαγγελίζεσθαι εἰρήνην, Romans 10:15 (R G Tr marginal reading in brackets); τό εὐαγγέλιον τῆς εἰρήνης, Ephesians 6:15; in the expression εἰρήνην ἀφίημι κτλ., John 14:27, in which Christ, with allusion to the usual Jewish formula at leave-taking (see 3 above), says that he not merely wishes, but gives peace; ἡ εἰρήνη τοῦ Χριστοῦ, which comes, from Christ, Colossians 3:15 (Rec. θεοῦ; τοῦ Θεοῦ, Philippians 4:7 (cf. Winers Grammar, 186 (175)). Comprehensively, of every kind of peace (blessing), yet with a predominance apparently of the notion of peace with God, εἰρήνη is used — in the salutations of Christ after his resurrection, εἰρήνη ὑμῖν (לָכֶם שָׁלום, Luke 24:36 (T omits; WH reject the clause); John 20:19, 21, 26; in the phrases ὁ κύριος τῆς εἰρήνης, the Lord who is the author and promoter of peace, 2 Thessalonians 3:16; ὁ Θεός τῆς εἰρήνης Romans 15:33; Romans 16:20; 2 Corinthians 13:1; Philippians 4:9; 1 Thessalonians 5:23; Hebrews 13:20; in the salutations at the beginning and the close of the apostolic Epistles: Romans 1:7; 1 Corinthians 1:3; 2 Corinthians 1:2; Galatians 1:3; Galatians 6:16; Ephesians 1:2; Ephesians 6:23; Philippians 1:2; Colossians 1:2; 1 Thessalonians 1:1; 2 Thessalonians 1:2; 2 Thessalonians 3:16; 1 Timothy 1:2; 2 Timothy 1:2; Titus 1:4; (Philemon 1:3); 1 Peter 1:2; 1 Peter 5:14; 2 Peter 1:2; 2 John 1:3; 3 John 1:15 (14); (Jude 1:2); Revelation 1:4. Cf. Kling in Herzog iv., p. 596f under the words Friede mit Gott; Weiss, Biblical Theol. d. N. T. § 83 b.; (Otto in the Jahrbb. fur deutsch. Theol. for 1867, p. 678ff; cf. Winer's Grammar, 549 (511)).

6. of the blessed state of devout and upright men after death (Wis. 3:3): Romans 2:10.