Webster's Dictionary 
(1): ( n.) The act of retributing; repayment.
(2): ( n.) That which is given in repayment or compensation; return suitable to the merits or deserts of, as an action; commonly, condign punishment for evil or wrong.
(3): ( n.) Specifically, reward and punishment, as distributed at the general judgment.
Baker's Evangelical Dictionary of Biblical Theology 
Hastings' Dictionary of the New Testament 
International Standard Bible Encyclopedia 
ret - ri - bū´shun :
1. New Testament Terms
2. A R evelation of Wrath as Well as Grace
5. Also the Positive Infliction of Divine Wrath
6. Instances of Use of Orge and Thumos
7. Instances of Use of Greek Words for "Vengeance"
8. Words Meaning "Chastisement" Not Used of the Impenitent
9. Judgment Implies Retribution
1. New Testament Terms:
The word as applied to the divine administration is not used in Scripture, but undoubtedly the idea is commonly enough expressed. The words which come nearest to it are ὀργή , orgḗ , and θυμός , thumós wrath attributed to God; ἐκδικέω , ekdikéō , ἐκδίκησις , ekdı́kēsis , ἔκδικος , ékdikos , and δίκη , dı́kē , all giving the idea of vengeance; κόλασις , kólasis , and τιμωρία , timōrı́a , "punishment"; besides krino , and its derivatives, words expressive of judgment.
2. A R evelation of Wrath as Well as Grace:
Romans 2 is full of the thought of retribution. The apostle, in Romans 2:5 , Romans 2:6 , comes very near to using the word itself, and gives indeed a good description of the thing: the day of wrath and revelation of the righteous judgment of God, "who will render to every man according to his works." It is well in approaching the subject to remind ourselves that there is undoubtedly, as the apostle says, a Revelation of wrath . We are so accustomed to think of the gracious revelation which the gospel brings us, and to approach the subject of the doom of the impenitent under the influence of the kindly sentiments engendered thereby, and with a view of God's gracious character as revealed in salvation, that we are apt to overlook somewhat the sterner facts of sin, and to misconceive the divine attitude toward the impenitent sinner. It is certainly well that we should let the grace of the gospel have full influence upon all our thinking, but we must beware of being too fully engrossed with one phase of the divine character. It is an infirmity of human nature that we find it difficult to let two seemingly conflicting conceptions find a place in our thought. We are apt to surrender ourselves to the sway of one or the other of them according to the pressure of the moment.
3. Witness of Natural Theology:
Putting ourselves back into the position of those who have only the light of natural theology, we find that all deductions from the perfections of God, as revealed in His works, combined with a consideration of man's sin and want of harmony with the Holy One, lead to the conclusion announced by the apostle: "The wrath of God is revealed from heaven against all ungodliness and unrighteousness of men" ( Romans 1:18 ). Wrath implies punishment, punishment is decreed, punishment is denounced. The word of God but confirms the verdict which conscience forecasts. Nature teaches that punishment, retribution, must follow sin. Within the sphere of physical law this is clearly exemplified. No breach of the so-called laws of Nature is tolerated. Strictly speaking, the laws of Nature cannot be broken, but let a man fail to keep in harmony with them, and the natural consequences will be trouble, punishment, retribution. Harmony with law is blessing; collision with law is loss. Thus law in Nature "worketh wrath" to the neglecters of it. Punishment necessarily results. So we may well expect that in the higher sphere, God's moral laws cannot be neglected or violated with impunity, and Scripture fully justifies the expectation and shows that sin must be punished. All things considered, the fact of punishment for sinners need not surprise; the fact of pardon is the surprising thing. The surprise of pardon has ceased to surprise us because we are so familiar with the thought. We know the "how" of it because of the revelation of grace. Grace, however, saves on certain conditions, and there is no such thing known in Scripture as indiscriminate, necessary, universal grace. It is only from the Bible that we know of the salvation by grace. That same revelation shows that the grace does not come to all, in the sense of saving all; though, of course, it may be considered as presented to all. Those who are not touched and saved by grace remain shut up in their sins. They are, and must be, in the nature of the case, left to the consequences of their sins, with the added guilt of rejecting the offered grace. "Except ye believe that I am he," said Incarnate Grace, "ye shall die in your sins" ( John 8:24 ).
4. Retribution the Natural Consequence of Sin:
Another conclusion we may draw from the general Scriptural representation is that the future retribution is one aspect of the natural consequence of sin , yet it is also in another aspect the positive infliction of Divine wrath . It is shown to be the natural outcome of sin in such passages as "Whatsoever a man soweth, that shall he also reap" ( Galatians 6:7 ); "He that soweth unto his own flesh shall of the flesh reap corruption" ( Galatians 6:8 ). It is not without suggestiveness that the Hebrew word ‛āwōn means both iniquity and punishment, and when Cain said "My punishment is greater than I can bear" ( Genesis 4:13 ), he really said "My iniquity is greater than I can bear"; his iniquity became his punishment. A due consideration of this thought goes a long way toward meeting many of the objections brought against the doctrine of future punishment.
5. Also the Positive Infliction of Divine Wrath:
The other statement, however, remains true and must be emphasized, that there is an actual infliction of Divine wrath . All the great statements about the divine judgment imply this, and while it is wrong not to take account of the natural working out of sin in its terrible consequences, it is equally wrong, perhaps more so, to refuse to recognize this positive divine infliction of punishment. This, indeed, is the outstanding feature of retribution as it assumes form in Scripture. Even the natural consequences of sin, rightly viewed, are part of the divine infliction, since God, in the nature of things, has conjoined sin and its consequences, and part of the positive infliction is the judicial shutting up of the sinner to the consequences of his sin. So in the case of Cain, his iniquity became his punishment, inasmuch as God sentenced him to bear the consequences of that iniquity. On the other hand, we might say that even the terribly positive outpourings of God's wrath upon the sinner are the natural consequences of sin, since sin in its very nature calls down the divine displeasure. Indeed, these two phases of future punishment are so very closely connected that a right view of the matter compels us to keep both before us, and no full explanation of the punishment is possible when either phase is ignored.
6. Instances of the Use of Orge and Thumos:
The terms in Scripture applied to the doom of sinners all imply divine displeasure, punitive action, retribution. The two outstanding Greek words for "wrath," orgē and thumos , are both freely applied to God. Orgē indicates settled displeasure, whereas thumos is rather the blazing out of the anger. The former is, as we should expect, more frequently applied to God, and, of course, all that is capricious and reprehensible in human wrath must be eliminated from the word as used of God. It indicates the settled opposition of His holy nature against sin. It was an affection found in the sinless Saviour Himself, for "he looked round about on them with anger" ( Mark 3:5 ). In the Baptist's warning "to flee from the wrath to come" ( Matthew 3:7; Luke 3:7 ), it is unquestionably the wrath of God that is meant, the manifestation of that being further described as the burning of the chaff with unquenchable fire ( Matthew 3:12 ). In John 3:36 it is said of the unbeliever that "the wrath of God" abideth on him. In Romans it is used at least 9 times in reference to God, first in Romans 1:18 , the great passage we have already quoted about "the wrath of God revealed from heaven." The connection is a suggestive one and is often overlooked. In the passage Paul has quite a chain of reasons; he is ready to preach the gospel at Rome for he is not ashamed of the gospel; he is not ashamed of the gospel for it is the power of God unto salvation; it is the "power of God" for therein is revealed the righteousness of God by faith; and this salvation by faith is a necessity " for the wrath of God is revealed," etc. Thus the divine wrath on account of sin is the dark background of the gospel message. Had there been no such just wrath upon men, there had been no need for the divine salvation. The despising of God's goodness by the impenitent means a treasuring up of "wrath in the day of wrath and revelation of the righteous judgment of God" ( Romans 2:3-5 ). God "visiteth with wrath" ( Romans 3:5 ).
In Romans 4:15 the apostle shows that "the law worketh wrath" (i.e. brings down the divine displeasure), while in Romans 5:9 he shows that believers are saved from wrath - undoubted wrath of God. The other two instances are in Romans 9:22 . Men are "by nature children of wrath" ( Ephesians 2:3 ); surely not "wrathful children," but liable to the wrath of God, and because of evil deeds cometh "the wrath of God upon the sons of disobedience" ( Ephesians 5:6; Colossians 3:6 ). Christ "delivereth us from the wrath to come" ( 1 Thessalonians 1:10 ); wrath has come upon the opposing Jews ( 1 Thessalonians 2:16 ); but believers are not appointed unto wrath ( 1 Thessalonians 5:9 ). With all these specific passages in view, to say nothing of the general teaching of the apostle on the question of coming judgment and punishment, it is utterly impossible to eliminate the idea of the divine displeasure against sinners, and His consequent retributive action toward them. Even Ritschl, who absolutely denies the great principle of retribution, of positive displeasure, admits that Paul teaches it; hence, the only way for him out of the difficulty is to reject Paul's teaching as unauthoritative. Other references to the "wrath of God" are in Hebrews 3:11; Hebrews 4:3; and 6 passages in the Apocalypse - Revelation 6:16 f; Revelation 11:18; Revelation 14:10; Revelation 16:19; Revelation 19:15 . Two of these refer to the "wrath of the Lamb," one of the most terrible phrases in the whole of the New Testament. Thumos is only used in the Apocalypse concerning God ( Revelation 14:10-19; Revelation 15:1-7; 16:1-19; Revelation 19:15 ). In each case it refers to the manifestation, the blazing forth of the wrath; in the last two passages it is used in combination with orgē , and is rendered "fierceness," the fierceness of His wrath.
7. Instances of Use of Greek Words for "Vengeance":
Ekdikeō , which means to avenge, is twice used of God ( Revelation 6:10; Revelation 19:2 ); and ekdikēsis , "vengeance," 6 times Luke 18:7 ff; Romans 12:19; 2 Thessalonians 1:8; Hebrews 10:30 ). In the first two instances it is used by Jesus concerning the divine action; ekdikos , "avenger," occurs once in application to God ( 1 Thessalonians 4:6 ); dikē , "judgment" or "vengeance" is twice used of God ( 2 Thessalonians 1:9; Judges 1:7 ). The use of these terms shows that the punishment inflicted on sinful men is strictly punishment of the vindicatory sort, the vindication of outraged justice, the infliction of deserved penalty. Very significant is the passage in 2 Thessalonians 1:6 , "It is a righteous thing with God to recompense affliction to them that afflict you." There is no question of bettering the offender.
8. Words Meaning "Chastisement" Not Used of the Impenitent:
It is very remarkable that the terms in Greek which would carry the meaning of punishment for the good of the offender are never used in the New Testament of the infliction which comes upon the impenitent; these are paideı́a and paideúō , and they are frequently used of the "chastisement" of believers, but not of the impenitent. It is often claimed that the word kolasis used in Matthew 25:46 carries the meaning of chastisement for the improvement of the offender, but although Aristotle, in comparing it with timōria , may seem to suggest that it is meant for the improvement of the offender (what he really says is that it is toú páschontos héneka , "on account of the one suffering it," "has the punished one in view," whereas timōria is toú poioúntos , "on account of the one inflicting" "that he may be satisfied"), the usage even in classical Greek is predominantly against making the supposed distinction. Both words are used interchangeably by the leading classical authors, including Aristotle himself, and kolasis is continually employed where no thought of betterment can be in question, while all admit that in Hellenistic Greek the distinction is not maintained, and in any case timōria is also used of the punishment of the sinner ( Hebrews 10:29 ).
9. Judgment Implies Retribution:
All the representations of the coming day of judgment tell of the fact of retribution, and Christ Himself distinctly asserts it. Apart from His great eschatological discourses, concerning which criticism still hesitates and stammers, we have the solemn close of the Sermon on the Mount, and the pregnant statement of Matthew 16:27 , "The Son of man shall come in the glory of his Father with his angels; and then shall he render unto every man according to his deeds," and all the apostolic teaching upon the solemn theme is but the unfolding of the same great thought.
10. Moral Sense Demands Vindication of God's Righteousness:
The conception of God as a perfect moral governor demands that His righteousness shall be fully vindicated. Looking at the course of history as it unfolds itself before us, we cannot fail to be struck with the anomalies which are presented. Righteousness does not always triumph, goodness is often put to shame, wickedness appears to be profitable, and wicked men often prosper while good men are under a cloud. Sometimes signal divine interpositions proclaim that God is indeed on the side of righteousness, but too often it seems as if He were unmindful, and men are tempted to ask the old question, "How doth God know? And is there knowledge in the Most High?" ( Psalm 73:11 ), while the righteous say in their distress, "Yahweh, how long shall the wicked, how long shall the wicked triumph?" ( Psalm 94:3 ). The moral sense cries out for some divine vindication, and the Scriptures, in harmony with this feeling, indicate that the final judgment will bring such vindication.
11. Scripture Indicates Certainty of Vindication:
In the Old Testament it is frequently presented as the solution of the baffling problems which beset the ethical sphere, as for instance in that fine utterance of religious philosophy in Psalm 73; the Psalmist has before him all the puzzling elements of the problem; the prosperity, the insolent and aggressive prosperity of the wicked, the non-success, the oppression, the misery of the righteous; he is well-nigh overwhelmed by the contemplation, and nearly loses his footing on the eternal verities, until he carries the whole problem into the light of God's presence and revelation, and then he understands that the end will bring the true solution.
So too the somber ruminations of the Preacher upon the contradictions arid anomalies and mysteries of human life, "under the sun," close in the reflection which throws its searchlight upon all the blackness: "This is the end of the matter:... Fear God, and keep his commandments; for this is the whole duty of man. For God will bring every work into judgment, with every hidden thing, whether it be good, or whether it be evil" ( Ecclesiastes 12:13 f). In the light of the same truth, the apostles labored, believing that when the Lord comes He "will both bring to light the hidden things of darkness, and make manifest the counsels of the hearts" ( 1 Corinthians 4:5 ). The more fully the subject is considered, the more we must feel that for the vindication of righteousness, the justification of the divine procedure, the rectification of wrongs, the explanation of mysteries, the reward and triumph of the righteous and the confession and punishment of the wicked, a great final, retributive judgment is Scriptural, reasonable, necessary.